Many of the bolded characters in the characterization above are apomorphies of subsets of streptophytes along the lineage leading to the embryophytes, not apomorphies of crown-group embryophytes per se.

All groups below are crown groups, nearly all are extant. Characters mentioned are those of the immediate common ancestor of the group, [] contains explanatory material, () features common in clade, exact status unclear.

Evolution.Ecology & Physiology. There is a variety of companion cell morphologies in the phloem. Transfer cells, companion cells with few plasmodesmata but numerous wall ingrowths, and intermediary cells, characterized by having numerous plasmodesmata that branch in the outer part of the walls adjacent to the bundle sheath cells, seem to be notably common in taxa found in this part of the tree (Turgeon et al. 2001; Turgeon 2010: Santalales and Berberidopsidales i.a. not included in study, see also Fabaceae, etc.). There seems to be a correlation between the presence of intermediary cells (see especially Lamiales) and the presence of raffinose and stachyose in the translocate, and active phloem loading of sugars is to be expected with such companion cell morphologies. This has a number of physiological consequences, while also keeping mesophyll tissue low in sugars that might otherwise attract and/or benefit herbivores (Turgeon 2010).

Phylogeny. See the Dilleniales page for discussion on the relationships around here; it is increasingly likely that Caryophyllales are sister to the asterids, whether (e.g. Bell et al. 2010) or not Dilleniales are sister to Caryophyllales.

Age. Crown-group Caryophyllales have been dated to 90-83 m.y.a. (Wikström et al. 2001: see position of Rhabdodendraceae); Anderson et al. (2005) suggests figures of 102-99 m.y., while Moore et al. (2010: 95% HPD, only two taxa included) estimated a mere (71-)67(-63) m.y. and Xue et al. (2012) the still younger ages of ca 64.4 or 50.4 (the lowest estimate) m.y., Magallón and Castillo (2009) ca 94.35 m.y., Bell et al. (2010: Rhabdodendraceae sister to the rest) an age of (115-)106, 99(-91) m.y., and Naumann et al. (2013) an age or around 78.7 m.y.. However some estimates of ages for nodes in Polygonaceae are more than 110 m.y. (Schuster et al. 2013), which, if confirmed, will call into question the dates of many of the other nodes in the order; Z. Wu et al. (2014) suggest a crown-group age of around 119 m.y.a., and ca 107.1 m.y.a. is the age suggested by Magallón et al. (2015).

X. Wang (2010a: p. 22) was inclined to the idea that Caryophyllales represented a very ancient clade: "Caryophyllales should represent, or at least is close to, the most primitive angiosperms". He compared their flowers to the reproductive structures of the coniferous Voltziales. Less cosmically, Doyle (2012) suggested that tricolpate pollen was "retained" in Caryophyllales.

Note: Possible apomorphies are in bold. However, the actual level at which many of these features, particularly the more cryptic ones, should be assigned
is unclear. This is partly because many characters show considerable homoplasy, in addition, basic information for all too many is very incomplete, frequently coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there is the not-so-trivial issue of how ancestral states are reconstructed (see above).

Cuénoud (2002a, b) summarizes variation in the order. There are many unusual
characters here, but their phylogenetic significance is unclear, partly
because of sampling problems; e.g. knowledge of anther wall development is poor (Dahlgren & Clifford 1982). Furthermore, members of the basal pectinations in the clade immediately below core Caryophyllales are particularly
poorly known. Ronse de Craene (2013: see Table 1) summarized aspects of perianth and androecium morphology and development in the order, optimizing a number of characters. Similarities in sieve tube plastids between Triplarieae (Polygonaceae) and core Caryophyllales are here treated as parallelisms (c.f. Judd & Olmstead 2004). Given the variation in carpel number in the clade, it is with some hesitation that three carpels is suggested as the plesiomorphic condition.

Ecology & Physiology. Cornwell et al. (2014) found that plants in this clade were characterized by being relatively small and having relatively high leaf nitrogen. Many
families are tolerant of saline/arid conditions, and the order is notable for the number of taxa than are halophytes, tolerating salt concentrations of 200mM (Flowers & Colmer 2008; Flowers et al. 2010), or that have a distinctive habit
(e.g. grapnel climbers) or physiology (carnivory, C4
pathway, CAM) or both. Perhaps associated with this, Lee et al. (2011) found that genes involved in metabolic processes involving sulphur compounds clustered at this node. It is noteworthy that sulphated phenolic compounds are also found in seagrasses (McMillan et al. 1980); here they occur in the [[Frankeniaceae +
Tamaricaceae] [Plumbaginaceae + Polygonaceae]] part of the tree in particular, and the plants with such compounds are often halophytic.

Plant-Animal Interactions. Some chrysomelid beetles - Alticinae, Cassidinae-Hispinae - seem notably more common here than elsewhere (Jolivet & Hawkeswood 1995), and some insects eat taxa in both main groups of this clade (Tempère 1969).

Bacterial/Fungal Associations. Landis et al. (2002) and Trappe (1987) suggested that both Polygonales and Caryophyllales (here just the one order) commonly lacked mycorrhizae, although there are some exceptions (e.g. some Nyctaginaceae and Amaranthaceae).

Purple-spored smuts and Uromyces rusts parasitize several
families, including Plumbaginaceae, Polygonaceae and core Caryophyllales (Savile 1979b: he considered this to be a strong sign that the groups were close).

Genes & Genomes. The rpl23 gene is a pseudogene in the few Caryophyllales examined (Logacheva et al. 2008).

For root hair development, see Dolan and Costa (2001). Carlquist (2010) suggests that few families in Caryophyllales have "truly adult" wood patterns. Placement of several features of wood anatomy on the tree need checking, although Carlquist (e.g. 2002b, 2003a, 2010) has provided a vast amount of detail (see also Core Caryophyllales). Non-bordered perforation plates may
be a synapomorphy for Caryophyllales or Caryophyllales and Santalales
(Carlquist 2000a; see also Carlquist 2010). Anomalous secondary thickening by successive cambia is widespread, as often occurs in lianes, and there is considerable variation in the morphology of these cambia (Carlquist 2010, much discussion). Maximally biseriate
rays are also widespread, including in Asteropeiaceae, but not in core Caryophyllales (Nandi et
al. 1998). For the leaf and stem anatomy of a number of halophytes of this clade, see Grigore et al. (2014).

The outer stamens are often
initiated in pairs, especially in core Caryophyllales, but also elsewhere in
the order (Ronse Decraene & Smets 1993). A petal and adjacent (antepetalous) stamen
are developmental units in Plumbaginaceae and Caryophyllaceae (Friedrich 1956;
Ronse Decraene et al. 1998). Tricellular pollen grains are common. Long style branches, or separate styles more or less joining at the apex of the ovary, are widespread. Carpels that are open in development are known both from Polygonaceae and core Caryophyllales (Tucker & Kantz 2001).

It is unclear where the character of starchy endosperm is to be put on the tree. The condition is unfortunately not known for taxa in the pectinations just below core Caryophyllales. Netolitzky (1926), however, noted that taxa he knew about and here included in core Caryophyllales lacked starchy endosperm, and starch was not recorded from the thin endosperm found in the seeds e.g. of some Amaranthaceae (Rocén 1927; Shepherd et al. 2005b and references), while its absence in the endosperm of Phytolacca (Woodford 1924) and Trianthema (Aizoaceae: Cocucci 1961) was also specifically noted. However, Bhargava (1935) recorded starch in the endosperm of Trianthema (Aizoaceae), Narayana and Lodha (1963) reported starch in the young endosperm of Orygia (and Corbichonia: Lophiocarpaceae), Kajale (1940b) noted dense starch grains in the mature endosperm of Amaranthaceae, and Kajale (1954) starch in the endosperm of Rivina humilis (Phytolaccaceae). Although several families of core Caryophyllales are reported to have starchy endosperm in the Flora of China (e.g. Dequan & Gilbert 2003), this must be confusion with the starchy perisperm. Those reports aside, the nature of any endosperm reserves in the Rhabdodendraceae to Cactaceae clade remains an open issue, and starchy endosperm is provisionally placed as an apomorphy for the Droseraceae to Polygonaceae clade alone.

Phylogeny. Hilu et al. (2003: matK analysis alone) suggest that Caryophyllales are sister to Asterids, a relationship that has been found in some other studies (e.g. Soltis et al. 1997, c.f. also Nandi et al. 1998). A relationship between Caryophyllales and Dilleniales has also been suggested (D. Soltis et al. 2003a). However, Caryophyllales alone (or perhaps with Santalales) now seem to be sister to the asterids, although the support is still only moderate; see the Pentapetalae page for further discussion.

Within Caryophyllales, Rhabdodendraceae were sister to the other members in an early rbcL analysis of Fay et al.
(1997b), in the Bayesian analysis of Soltis et al. (2007a) and also in Bell et al. (2010). Cuénoud et al. (2002) found that Simmondsia was grouped with Rhabdodendron in a matK analysis, but with only weak support, but in two- and four-gene analyses (with poorer sampling) it was associated with core Caryophyllales; in trees shown by Drysdale et al. (2007) and Brockington et al. (2007, esp. 2009) a position of Rhabdodendron as sister to the rest of core Caryophyllales was again found in most analyses, and is adopted here (see also Soltis et al. 2011). Hilu et al. (2003: matK analysis alone) also suggested relationships between Rhabdodendraceae and that part of the tree.

There are two main groups within Caryophyllales, one the core Caryophyllales, the old Centrospermae, and four small families associated with them, and the other includes Polygonaceae, etc., and a number of carnivorous taxa like Nepenthaceae and Droseraceae. This latter clade is well-supported (Morton et al. 1997b; Soltis et al. 2011), although it was not recovered in the mitochondrial analysis of Qiu et al. (2010) and relationships within it are scrambled in Bell et al. (2010). It includes four carnivorous
families that have attracted a lot of attention (see also Albert et al. 1992; Meimberg et al. 2000; Cuénoud et al. 2002; Cameron et al. 2002; Renner & Specht 2010) and other families
with distinctive vegetative morphologies (see also Heubl et al. 2006).

Within the other major clade, Asteropeiaceae and Physenaceae form
a well supported pair, in turn showing a well-supported sister group
relationship to core Caryophyllales (Källersjö et al. 1998). Similarly, Asteropeiaceae
and Simmondsiaceae, the only two taxa from this part of the order that were included, were successively sister groups to the
core (D. Soltis et al. 2000). The tree below is based largely on those presented by Meimberg et al. (2000), Cameron et al. (2002: 4 genes) and Cuénoud et al. (2002: matK alone). For relationships within the core Caryophyllales, which are still only partly understood, see below.

Previous Relationships. Takhtajan's (1997) Plumbaginanae
are monotypic; Nepenthanae included Droseraceae and some other Caryophyllales,
but also families now in Ericales, etc. Many of the families in Caryophyllales were included in Cronquist's (1981) Caryophyllidae. Plumbaginaceae are rather similar in a few respects to Primulaceae and relatives and the two have been considered close in the past (see Cronquist 1981 for discussion); Friedrich (1956) had effectively discounted such ideas.

Age. The age of this clade is perhaps 75-67 m.y, (Wikström et al. 2001); the crown group age in Bell et al. (2010: [Frankenia + Tamarix] sister to the rest) is (100-)91, 86(-77) m.y., while ca 99.3 m.y.a. is the age in Magallón et al.( 2015).

Evolution.Divergence & Distribution. For gland morphology and vascularization in this part of the tree, see T. Renner and Specht (2011); optimisation is not easy. Although sessile, stalked and pit glands are found in the [Plumbaginaceae + Polygonaceae] clade, how similar they are to stalked glands found in some members of the carnivorous clade, and also to the sessile to depressed salt glands in the [Frankeniaceae + Tamaricaceae] clade is unclear; T. Renner and Specht (2011) did not include the latter clade in their study. Conran et al. (2007) noted that Frankeniaceae, Tamaricaceae and Plumbaginaceae all have flat, multicellular glands of subepidermal origin. This is perhaps an apomorphy there (or still higher), with a loss in Polygonaceae.

Chemistry, Morphology, etc. For the vegetative morphology of carnivorous members of this clade, see Kaplan (1997, vol. 2: chap. 18). The acetogenic naphthoquinone plumbagin is known from
Plumbaginaceae, Droseraceae, Nepenthaceae, and Dioncophyllaceae, and related compounds are found
in Polygonaceae (Culham & Gornall 1994; Kovácik & Repcák 2006).

Age. The age of this node in Bell et al. (2010) is (90-)77, 72(-60) m.y., but note the topology there; ca 83 m.y.a.a is the age suggested by Magallón et al. (2015).

Evolution.Divergence & Distribution. For a synapomorphy scheme for the whole group,
see in part Albert and Stevenson (1996), Meimberg et al. (2000:
the floral characters listed are mostly plesiomorphies), but especially Heubl et al. (2006).

Heubl et al. (2006) suggest that fly-paper traps are the plesiomorphic condition for the group, but where features like this or the possession of circinate leaves and pollen tetrads are placed on the tree will depend on the model of character optimisation used.

Ecology & Physiology. The acquisition of carnivory may have
happened more than once here, or it occurred once and then was lost, perhaps more likely given the topologies found (Meimberg et al. 2000; Cameron et al. 2002: see also Schlauer 1997). T. Renner and Specht (2011) suggest scenarios for the evolution of digestive glands, and find that novel chitinase genes - otherwise involved in anti-fungal activities - have become involved in the extracellular degradation of the chitin of arthropods in this clade (T. Renner & Specht 2012).

Chemistry, Morphology, etc. Heubl and Wistuba (1997) suggested that both
Droseraceae and Nepenthaceae had ploidy levels of 8 or 16, based on x = 5 or
thereabouts.

For information on acetogenic quinones and alkaloids,
see Hegnauer (1986), Bringmann and Pokorny (1995) and Bentley (1998), for carnivory, see Lloyd (1942) and Juniper et al. (1989), and for general information, especially photographs, see McPherson (2010).

Phylogeny. Metcalfe (1952a) suggested relationships between members of this group based on anatomical similarities. Williams et al. (1994) drew
atttention to possible relationships between Dioncophyllaceae and Drosophyllum in particular, and
Drosophyllum and Nepenthaceae were also found to be weakly associated (Morton et al.
1997b). Soltis et al. (2011) found Drosera and Nepenthes to be sister taxa, but the support was only moderate and sampling not extensive. For detailed relationships, see Meimberg et al. (2000) and Cameron et al. (2002); Drosophyllaceae are sister to Dioncophyllaceae + Ancistrocladaceae, with good support, in an analysis of matK sequences, the position of Nepenthaceae being uncertain (Cuénoud et al. 2002). Indeed, Crawley and Hilu (2013: two genes) found either a weakly supported [Nepenthaceae + Droseraceae] clade, or Nepenthaceae were sister to the rest of the group, depending on the method of analysis.

Droseraceae are insectivorous herbs usually with
adaxially coiled or folded leaves and moderate-sized flowers; there are
three carpels usually terminated by branched styles.

Evolution.Divergence & Distribution. The beginning of diversification within Drosera may date to ca 42 m.y.a., although a pre-continental drift time has also been suggested (Yesson & Culham 2006 and references). Drosera is exceptionally diverse in S.W. Australia, where there are about one third of the species in the whole genus; diversification may be linked to the onset of the Mediterranean climate there some 15-10 m.y.a. The Australian pygmy sundew clade includes D. meristocaulis, a plant from Guyana (Rivadavia et al. 2012).

Ecology & Physiology.Aldrovandra and Dionaea both have snap-traps with multicellular trigger hairs, etc. (Cameron et al. 2002). The traps of Dionaea close in about 100 ms, the movement being aided by the leaf blades changing from concave to convex in shape (Forterre et al. 2005), while in the snap traps of Aldrovanda the blade does not change shape, but the midrib does (Poppinga & Joyeux 2011); Volkov et al. (2008), Escalante-Pérez et al. (2011) and Volkov and Markin (2014) provide details of the physiological mechanisms involved in the former genus. Gibson and Waller (2009; see also Williams 2002) discuss the evolution of the snap traps of Dionaea, which are unique in angiosperms; it is perhaps associated with the capture of larger prey than the plant could otherwise utilize.

Indeed, there is quite a variety of different hair types in Drosera itself, and some of these may be comparable with the marginal spines of Dionaea (Hartmeyer & Hartmeyer 2010; Hartmeyer et al. 2013)). Thus the leaves of Drosera glanduligera have rapidly-moving eglandular marginal hairs that can snap tight in as little at 75 ms and that pin the prey against glandular hairs in the centre of the blade (Poppinga et al. 2012). The glands of at least some species of Drosera produce a ribonuclease which may aid the plant in obtaining phosphorus from its prey, and perhaps also in defence against viruses (Okabe et al. 2005). For further literature, see Peroutka et al. (2008b).

Chemistry, Morphology, etc. Metcalfe and Chalk (1950) describe distinctive vascular
patterns in the inflorescence axis and petiole. In Drosera aliciae young inflorescences (before flower buds are evident) appear to have abaxially circinate vernation, but this is probably a reflection of the way the monochasial cyme is developing.

The pollen of Droseraceae is remarkable. When the pollen is hydrated, there are protrusions along the borders of adjoining grains, and in Dionaea and Drosera regia these protrusions persist in the dehydrated state and are operculate (Halbritter et al. 2012).

Phylogeny.Aldrovandra and Dionaea may be sister taxa; both have snap-traps, n = 6, etc. (Cameron et al. 2002; Rivadavia et al. 2003: little support for the relationship); see also Williams et al. (1994) for phylogeny. Rivadavia et al. (2003) discuss the phylogeny of Drosera. The position of D. regia is unclear; in both chromosome number and pollen morphology (it has operculate protrusions in the pollen) it is rather different from other species of Drosera; it may be sister to the rest of the genus, or even closer to other genera in the family.

Age.Nepenthes is known fossil as pollen from Europe in the Eocene (Krutzsch 1989).

Nepenthaceae are often insectivorous plants that are easy to
recognize because of the lidded pitchers borne on the end of a twining
prolongation of the leaf. The leaf base itself is broad, further widening to form a laminar portion that then narrows to form the twining portion. The plants are
dioecious, the inflorescences are racemes, the flowers are rather inconspicuous,
and the seeds are very small.

Evolution.Divergence & Distribution. For the biogeography of Nepenthes, see Meimberg and Heubl (2006). Some analyses suggest that the Malesian Nepenthes (including species from New Caledonia and Australia) are derived from a stock represented by the extant taxa found to the west of Malesia, but different relationships are suggested by different genes.

Ecology & Physiology. Pavlovic et al. (2007) discuss the physiology of lamina and trap (see also Mithöfer 2011 and references). The liquid in the tank tends to be acid, and contains enzymes from the plant (Peroutka et al. 2008b; Adlassnig et al. 2011), however, how insects are trapped in the pitchers has long been unclear. Nectar is produced by the pitchers and attracts insects. Recent work suggests that the rim (peristome) of the pitcher is extremely wettable, and insects may aquaplane when they step on it, falling in to the pitcher below where they die and get digested; when the rim is dry insects walk on it easily, but they still may get trapped if the plant has wax-covered inner pitcher walls (Bohn & Federle 2004). The main capure mechanisms correlate with climate, species with epicuticular waxes being found in drier climates (Moran et al. 2013). Interestingly, the ant Camponotus schmitzi lives in close association with Nepenthes bicalcarata, and it can run across even the wetted rim. For the fauna living in the liquid in the pitchers, see Kitching (2000).

On the whole the pichers seem not to be very efficient at capturing insects (Joel 1988), and the traps may have other functions. It has recently been found that some species of Nepenthes with particularly large pitchers capture the faeces of tree shrews (Tupaia montana) as they feed from glands on the inner surfaces of the lids (Chin et al. 2010), and in other cases nutrients from litter that falls into the trap may be taken up by the plant (Adlassnig et al. 2011 and references).

Although mimicry with flowers has sometimes been invoked as an explanation of the distinctively coloured and shaped pitcher-rims, this is unlikely (Joel 1988; Ruxton & Schaefer 2011).

Chemistry, Morphology, etc. The expanded part of leaf is developed from
the leaf base, as in many monocots, the twining petiole and the pitcher from the rest (e.g. Troll 1932); the leaf is epiascidiate, i.e. the inside of the pitcher is developmentally equivalent to the adaxial surface of the lamina, the outside to the abaxial surface.

The outer integument develops
greatly after fertilization and forms an exostome (Goebel 1933); there is a
hair-pin bundle in the testa (Takhtajan 1988).

For general information, see Cheek and Jebb (2001: almost a monograph), Kubitzki (2002d), McPherson (2008) and the Carnivorous Plants Database, for chemistry, see Hegnauer (1966, 1990), for anatomy, Metcalfe (1952a) and Pant and Bhatnagar (1977).

Phylogeny. For some relationships within Nepenthes, see Meimberg and Heubl (2006). Nepenthes pervillei, from the Seychelles, and N. madagascariensis were successively sister to the rest of the genus, although support was weak (Alamsyah & Ito 2013).

Drosophyllaceae are subwoody carnivorous plants that may be recognised by their long,
abaxially coiled leaves that have sticky, glandular hairs in longitudinal lines on their abaxial
surfaces; these hairs are not sensitive. The flowers are relatively large and short-lived (they remain open only a single day), but the petals dry and persist around the capsule.

Although Drosophyllum looks quite delicate, it grows in very dry conditions and does not dry out fast. The mucilage on the tentacles is hygroscopic and may help the plant maintain a positive water balance (Adamec 2009).

Age. Bell et al. (2010) suggested an age for this clade of (61-)41, 37(-20) m.y., Wikström et al. (2001) an age of 47-29 m.y.; around 36.2 m.y.a. is the age in Magallón et al. (2015).

Chemistry, Morphology, etc. For the distinctive napthyl isoquinoline alkaloids of the clade, see Bringmann (1986), Bringmann and Pokorny (1995), and Bringmann et al. (2008, and references); they are synthesised from polyketide precursors, not from aromatic amino acids, so are barely alkaloids in the strict sense. For growth patterns see Cremers (1974).

Ancistrocladaceae are lianes that can be recognised by their shortly
petiolate, extsipulate, entire leaves with glands in pits on the abaxial
surface, and the complex, branched stem grapnels that are often opposite tufts of leaves on short shoots
leaves.

Chemistry, Morphology, etc. 1/3 species tested had fluorescing wood. Minute stipules and flowers with
four carpels are reported by Takhtajan (1997) and Porembski (2002). The pollen is like that of
Dioncophyllaceae (Cronquist 1981).

For a little anatomy, see Metcalfe (1952a; more in van Tieghem 1903b), for chemistry, see Hegnauer (1989) and for general information, see Keng (1967a), Porembski (2002) and Heubl et al. (2010).

Previous Relationships. In the past Ancistrocladaceae have often been included in Violales or in Theales or Theanae (Cronquist 1981; Takhtajan 1997).

Dioncophyllaceae are distinctive in their rather long
rosette leaves with closely parallel venation and then, in the climbing phase, by leaves that have paired grapnel hooks at
the apex. The fruits open before maturity and
expose the still-developing disciform, winged seeds.

Evolution.Ecology & Physiology. Some leaves in young plants of Triphyophyllum peltatum have a short blade and glandular hairs on the abaxial surface of the
midrib, which is prolonged beyond the blade (Green et al. 1979) - and they are abaxially circinate when young, just like the leaves of Drosophyllum. It is at this stage that the plant may capture insects (Bringmann et al. 2001).

For anatomy, see Metcalfe (1952a) and Miller (1975), for gross morphology, see Airy Shaw (1952), Gottwald and
Parameswaran (1968) and Schmid (1964), for growth (the curved hooks are series of sympodial units) and seedlings, see Cremers 1974), for chemistry, Hegnauer (1966, as Flacourtiaceae, 1989) and Spencer and Siegler
(1985), and for general information, see Porembski and Barthlott (2002), McPherson (2008: excellent photographs), and the Carnivorous Plants Database.

Previous Relationships. See Airy Shaw (1952) for a summary. Dioncophyllales were included in
Theanae by Takhtajan (1997) and in Violales by Cronquist (1981).

Evolution.Divergence & Distribution. It is equally parsimonious to assume that petal appendages are apomorphies for the family pair as it is to assume that they have evolved independently. In Tamaricaceae members of the Reamuria, sister to the rest of the family, clade have these appendages. Seeds with copious endosperm have the same distribution.

Chemistry, Morphology, etc. For salt glands, see Fahn (1979 and references) and the discussion above, for ovules, etc., see Mauritzon (1936b).

Phylogeny. The monophyly of the two families and their sister-group relationship have been confirmed by Gaskin et al. (2004).

Previous Relationships. Both Frankeniaceae and Tamaricaceae were placed in Violales by Cronquist (1981) and in Violanae by Takhtajan
(1997), probably because of their parietal placentation.

Chemistry, Morphology, etc. Some information is taken from Walia and Kapil (1965),
Whalen (1987: taxonomy Old World Frankenia) and Olson et al. (2003: anatomy); for general accounts, see Surgis (1921) and and Kubitzki (2002d).

Tamaricaceae are woody plants with small leaves and flowers; the styles are long and the branches are terminated by expanded stigmas. The capsular fruits open to release hairy seeds.

Chemistry, Morphology, etc.Reamuria is distinctive in having single terminal flowers, a
contorted corolla, and basal adaxial scales on the petals, c.f. Frankeniaceae. It also has many
centrifugal stamens arising from 10 primordia, it lacks a nectary, and its seeds have endosperm (Ronse Decraene 1990).

See Frisendahl (1912), Joshi and Kajale (1936) and Johri and Kak (1954) for embryology, Hegnauer (1973, 1990) for chemistry, Czaja (1978) for seed
storage, Zhang et al. (2001) for pollen and Gaskin (2002) for a general account.

Evolution.Divergence & Distribution. This whole clade may be most diverse immediately away from the tropics (see Kostikova et al. 2014b for Polygonaceae).

Plant-Animal Interactions. Lycaeninae caterpillars are quite commonly found on this family pair, probably because of the polyphenolics in their leaves (Fielder 1995).

Chemistry, Morphology, etc. For sterol composition in comparison to that of core Caryophyllales, see Wolfe et al. (1989), for anatomy, see Carlquist and Boggs (1996). There are early reports that both families have perisperm (see Rocén 1927, p. 169).

Plumbaginaceae are perennial herbs or shrubs, rarely climbers. They can be recognised by their leaves which
have broad bases and are frequently only shortly petiolate and/or with entire
margins, and their flowers which have a relatively large, persistent, and
sometimes colored calyx (which can be very well developed in fruit, forming a circular wing) and antepetalous stamens. The single ovules borne at the ends of long, curved funicles are
easily enough seen on dissection.

Evolution.Divergence & Distribution. Lledó et al. (2005, see also 2011) suggest a number of ages for nodes in Limonioideae; calibration was on the age of the island the endemic Limonium endroides inhabited that was used as a maximum age.

Limonieae are most diverse in the area from the western Mediterranean to Central Asia. In the former area about half the 90 species of Armeria
are from the Iberian Peninsula, while in Limonium there is hybridization and hundreds of microspecies, some apomictic. In Central Asia genera like Acantholimon are common (Lledó et al. 2005, 2011).

Ecology & Physiology. Members of the family prefer saline and sometimes rather dry conditions. Species of Limonium and some other Limonieae are succulent halophytes and grow in salt marshes (Hanson et al. 1994; Flowers & Colmer 2008; Ogburn & Edwards 2010) while Aegilitis of the Aegalitideae is a mangrove plant. The quaternary ammonium
compounds of one sort or another that have been found in practically all members of the family examined are involved in salt excretion, while choline O-sulphate may be involved in sulphate detoxification (Hanson et al. 1994).

Pollination Biology & Seed Dispersal. In a number of Limonieae the calyx becomes scarious in fruit and helps in wind dispersal; in Plumbago the calyx with its sticky glands persists in fruit and attaches to a passing animal.

Chemistry, Morphology, etc. Glycine betaine is known from only a very few species of Limonium (and from Plumbago, etc.), but not from Aegalitis and Armeria and other Limonieae (Rhodes & Hanson 1993; Hanson et al. 1994); see Hanson et al. (1994) for choline-O-sulphate distribution.

For wood anatomy, which may be paedomorphic, the family perhaps having a more or less herbaceous ancestry, see Carlquist and Boggs (1996). There is extensive gross anatomical variation that probably can be integrated with the tribes/subfamilies - for example, there is a continuous ring of sclerenchyma outside the phloem in Plumbaginoideae, separate fascicles in Limonioideae, etc. (see Maury 1886). Williams et al. (1994) suggested that it was not known if the mucilage
glands were vascularized, although in their data matrix the family was scored
as having vascularized glands (see also the discussion above). Leaf vernation is variable, being flat,
convolute or involute.

The style branches of Armeria are papillate all around for their entire lengths. Many Plumbaginoideae seem to lack a protruding obturator (Dahlgren 1916). According to Dahlgren (1916), the embryo sac is tetrasporic but eight-nucleate, but Maheshwari (1947) suggested it was tetrasporic and four-celled, three of the megaspores fused and the mature embryo sac consisted of an egg cell, a single synergid, a tetraploid polar nucleus and a three-nucleate antipodal cell... Aegalitis is little known.

Phylogeny. Lledó et al. (1998, 2001) suggest phylogenetic relationships within the group. For a phylogeny focusing on Limonium, see Lledó et al. (2005), and for one focussing on Acantholimon, see Moharrek et al. 2014), where relationships are [Acantholimon [Limonium + Armeria]], in the latter study, the old sections of Acantholimon were pulverized. Aegialitis is placed as sister to all the rest of the
family in some analyses (Savolainen et al. 2000: rbcL only).

Classification. The classification here is based on the phylogeny in Lledó et al. (1998, 2001). There are a number of monotypic genera in Limonieae (Kubitzki 1993b).

Previous Relationships. Plumbaginaceae used to be associated with
Primulaceae-Primuloideae. Both have stamens opposite the petals, common petal-stamen primordia, and a ±
connate corolla (the latter especially in Limonioideae), but the two are not close - for Primulaceae, see Ericales.

Age. This age of this node has been estimated at (122.5-)105.5, 97.8(-78.2) m.y. (Schuster et al. 2013), and (97.3-)90(-73.7) m.y.a. (Kostikova et al. 2014b: p. 1862, it "split[] from Plumbaginaceae"??).

The flowers of Polygonaceae are rather small but 3 to 6 perianth members persist or become enlarged, surrounding the
fruit proper, an achene that is often angled. A sheathing stipule is common and the
nodes of the herbaceous taxa in particular are more or less swollen. Eriogonum and relatives lack the distinctive stipule and have more or less cymose and involucrate
inflorescence units.

Evolution.Divergence & Distribution. If Oxygonum is sister to [Polygonaceae + Eriogonoideae], it may suggest that Polygonaceae were originally African/Gondwanan, and if age estimates here are accurate, then drift can be implicated in some distributions in the family (Schuster et al. 2011b, see also 2013). Eriogonum and relatives are very diverse in the drier regions of southwest North America (and there are also some species in southern South America), and may represent a relatively recent radiation (Sanchez & Kron 2008). See Schuster et al. (2013) for more dates within the family.

For a detailed discussion on the biogeography of [Polygonoideae + Eriogonoideae], especially Muehlenbeckia, with additional ages, see Schuster et al. (2013). Diversity within the family as a whole peaks in more temperate regions rather than increasing towards the tropics; reduced extinction rates in temperate clades may be an explanation (Kostikova et al. 2014b). Diversification within Rheum occurred along with the uplift of the Tibetan Plateau in the last (16.1)-12.0, 9.9(-6.8) m.y. (Sun et al. 2012). For the evolution of extra-floral nectaries in Polygoneae - no real effect on diversification rate - see Weber and Agrawal (2014).

The speciose Eriogonum is a feature of drier areas of western North America, and perennial species may have broader niches than annual species, despite a contrary expectation based on the shorter generation times of the latter (Kostikova et al. 2013: focus on Californian species). However, the perennial species have to be able to put up with fluctuating environmental conditions, while the annuals can live their lives when conditions are suitable. For adaptive evolution and parallelism/convergence in Californian Eriogonum and relatives, see Kostikova et al. (2014a).

Polygonum (Bistorta) viviparum is a common perennial, herbaceous ECM plant of the tundra, both as a pioneer and as a component of more established vegatation (e.g. Gardes & Dahlberg 1996; Michelsen et al. 1998; Brevik et al. 2010).

Pollination Biology. Remarkable "glasshouse bract" inflorescences with large white recurved inflorescence bracts covering the flowers have evolved twice within Rheum growing at high altitudes in Southeast Asia (Sun et al. 2012), a parallelism evident at the molecular level (Liu et al. 2015). In Rheum nobile the fungus gnat Bradysia pollinates the flowers, also laying eggs at the same time; the association is mutualistic - pollination is effected, but some of the developing fruits are eaten by the developing larvae (Song et al. 2014).

Plant-Animal Interactions.Lycaena and Heliophorus (Lycaenini) are found on Polygonaceae throughout their extratropical range (Ehrlich & Raven 1964), and caterpillars of the lycaenid Euphilotes eat a number of species of Eriogonum (Shields & Reveal 1988).

Genes & Genomes. Some species of Rumex have an
X-Y system determining the 'sex' of the plant; polyploids may have only a single Y chromosome (Cuñado et al. 2007).

See Logacheva et al. (2008) for the expansion of the inverted repeat.

Chemistry, Morphology, etc. Williams et al. (1994) noted that although no plumbagin had been
reported from the family, other quinones were known there.

Sieve tube plastids with protein fibres are reported from Triplarieae
(Behnke 1999). The climber Antigonon has leaf
tendrils and successive cambia (Carlquist 2003a). There are often subepidermal
strands of collenchyma or sclerenchyma in the stem in Polygonaceae (see also Plumbaginaceae).

There have been suggestions that the perianth of Polygonaceae is basically 3-merous and two-whorled; the
carpels are opposite the outer perianth whorl (e.g. Galle 1977 for floral diagrams, etc.; see also Laubengayer 1937; Ronse Decraene 1989a; Vautier 1949: comprehensive survey of floral vasculature). Flowers with five tepals would then be derived from those with six, perhaps by fusion of two of the members. Recent work, however, suggests that the basic condition for the family is to have five perianth members (Lamb Frye & Kron 2003; Burke et al. 2009, esp. 2010; Ronse de Craene & Brockington 2013). However, the extensive earlier work on floral vascularization is not integrated into this scenario, and floral vascularization in Symmeria, Afrobrunnichia and Oxygonum, phylogenetically critical taxa (see below) is unknown.

Stamens in Fagopyrum are both
introrse and extrorse (Le Maout & Decaisne 1868), while in Persicaria campanulata five stamens are adnate to the perianth and three are completely free (Ronse Decraene & Akeroyd 1988). Since a nucellar beak is usually (?always) developed, there are several (4+) layers of parietal tissue. The chalazal end of the seed, i.e. the part below the point of junction of the integuments, van be quite massive (Cocucci 1957). The exact nature of the funicle is unclear;
it might be a reduced basal placenta.

Phylogeny. in the past, the largely herbaceous Eriogonoideae s. str., i.e. Eriogonum and its immediate relatives, were separated from Polygonoideae, variable in habit. The former lacked a sheathing stipule, their inflorescence was cymose and had an involucre, while the latter had a sheathing stipule and a racemose inflorescence that lacked an involucre. However, there are two moderately/well supported major clades in the family, one largely woody, Eriogonoideae s.l., Eriogonoideae s. str. being derived within that clade, and the other, Polygonoideae, largely herbaceous (Cuénoud et al. 2002; Lamb Frye & Kron 2003; Burke et al. 2010; Sanchez et al. 2011).

Some genera are basal to these two clades. Symmeria and Afrobrunnichia - the position of latter is not so clear - may be immediately below the [Antigonon + Brunnichia] clade in Eriogonoideae (Sanchez et al. 2009a; Sanchez & Kron 2009; see also Burke et al. 2009). However, Sanchez et al. (2009b) using chloroplast data placed Symmeria as sister to the whole of the rest of the family and Afrobrunnichia sister to Eriogonoideae, while ITS data suggested that Afrobrunnichia was sister to Polygonoideae and Symmeria sister to Eriogonoideae; in a combined analysis the relationships were [Symmeria [Afrobrunnichia [the rest of the family]]]. Not all support values were high, but this set of relationships was found by Schuster et al. (2011b), who also noted that the position of Oxygonum was uncertain, although it, too, might be part of a basal pectination (see also Burke et al. 2010 and Sanchez et al. 2011 for the position of Symmeria).

Eriogonoideae s. l. include the woody "Coccolobeae" which appear to be both basal and paraphyletic (e.g. Cuénoud et al. 2002; Lamb Frye & Kron 2003); [Antigonon + Brunnichia] (Brunnichieae), both lianes, are sister to the rest of the woody clade (Sanchez & Kron 2008; Burke et al. 2010; Schuster et al. 2013: Symmeria etc. not included). Within the rest of Eriogonoideae are clades with 5 and 6 perianth members, although the 5-membered Podopterus may be sister to the 6-membered clade (Burke et al. 2010). Eriogonum is paraphyletic and includes taxa like Chorizanthe and Dedeckera (Sanchez & Kron 2006, 2008); indeed, although tribal limits in the old Eriogonoideae are holding up, subtribes and below are in somewhat of a state of disrepair (Kempton 2012).

Genera like Persicaria and Bistorta make up Persicarieae, sister to other Polygonoideae (Schuster et al. 2013). The mostly viney Muehlenbeckia is to be included in Polygonoideae; most species are sister to Fallopia (Schuster & Kron 2008; Schuster et al. 2011a, esp. 2013). For a molecular phylogeny of Polygoneae, see Schuster et al. (2011b, also below). Rheum shows substantial morphological variation but little molecular variation, at least in the markers analysed (Wang et al. 2005).

Evolution.Divergence & Distribution. Few (1-2) ovules per carpel may be an apomorphy for the whole clade, but the position of these ovules varies - apical in Simmondsiaceae, and basal in Rhabdodendraceae, just for starters. Basifixed anthers and stamens with very short filaments are common outside core members of this clade; their optimisation on the tree is difficult. Taxa with such stamens also lack floral nectaries.

Rhabdodendraceae are smallish evergreen trees that may be recognised by their
fringed-peltate hairs, their rather large, entire, pellucid-punctate, and exstipulate leaves. The leaves are rather congested and grade into much smaller undifferentiated leaves at the beginning of each innovation. The flowers have stamens with short filaments and long anthers, and a single
carpel with a basal style. The fruit is distinctive, the drupe being held in a cup-shaped structure formed by the
persistent calyx and swollen pedicel apex.

Chemistry, Morphology, etc. I have not seen stipules (see also Puff & Weber 1976; c.f. Prance 1972c),
but the rather broad petiole base can be confused with them.

The ovule is often described as being
unitegmic (e.g. Nandi et al. 1998, following Puff & Weber 1976), but see
Tobe and Raven (1989). The stylulus may be stigmatic for only part of its length. The embryo is surrounded largely by
testa that develops from the unitegmic part of the ovule, and the description above refers to this (Tobe & Raven 1989).

For general information, see Prance (2002), for some chemistry, see Wolter-Filho et al. (1989). .

Previous relationships. The position of Rhabdodendraceae
has long been uncertain. Thus they were
placed in Rutales by Takhtajan (1997), although Prance (1968) had much earlier suggested a position around Caryophyllales; Cronquist (1983) placed them at the end of his Rosales after Surianaceae.

Evolution.Divergence & Distribution. A uniseriate perianth is tentatively pegged to this node, the implication being that petal-like structures common in members of this clade are in fact staminodial or calycine in origin (Ronse de Craene 2007); see also Brockington et al. (2009), Ronse de Craene and Brockington (2013), and the discussion below under Core Caryophyllales.

Simmondsiaceae are evergreen shrubs that may be
recognised by their opposite leaves that are clearly articulated near the stem
and have flat, rather thick blades with entire margins. The staminate flowers are small and borne in
terminal inflorescences while the carpellate flowers are single and axillary;
the calyx is much enlarged in fruit.

Chemistry, Morphology, etc. The large embryo contains liquid wax made up of esters of high molecular weight, mono-ethylenic acids. The stamens are
described as being latrorse (Takhtajan 1997).

For general information, see van Tieghem (1897: cork ?superficial), Mathou (1939) and Köhler (2002), for embryology, see Wiger (1935), for chemistry, see Hegnauer (1989, as Buxaceae), for testa anatomy, etc., see Tobe et al. (1992), and for wood anatomy, see Carlquist (2002b).

Previous Relationships. Simmondsiaceae have usually been
included in Buxaceae or placed in a separate family, but close to Buxaceae. However, a monotypic Simmondsiales
have been included in Hamamelididae (Takhtajan 1997).

Asteropeiaceae are evergreen trees that may be
recognised by their shortly petiolate leaves whose blades are entire, exstipulate, and with rather indistinct venation. The flowers are small and are in terminal panicles, the fruit has a single seed, and the calyx is much accrescent and spreading.

Physenaceae are rather undistinguished with their more
or less two-ranked, entire, exstipulate and coriaceous leaves. The flowers lack a corolla, the stamens have
a very thin filaments and long anthers, and the styles are long. The fruit is inflated and contains a single
seed which apparently has a vascularized seed coat.

Chemistry, Morphology, etc. The petiole is often described as
being articulated; it commonly breaks transversely above the base, but there is no evidence that the leaf is derived from a compound leaf. The vascular bundles in the lamina are completely surrounded by mechanical tissue. There are
brachysclereids in the secondary phloem and the placental bundles are inverted (Dickison & Miller 1993).

General information is taken from
Morton et al. (1997b) and Dickison (2002); for triterpene glycosides, see Inoue et al. (2009).

Previous Relationships. Physenaceae were included in Urticales by Cronquist
(1981) and placed in a monotypic Physenales in Dilleniidae by Takhtajan (1997).

The evolution of petals, betalains and anomalous secondary thickening in this group has long been of interest, but our understanding of phylogenetic relationships in this area is still uncertain in places (see below). Detailed sampling of Phytolaccaceae as well as Molluginaceae is critical if we are to understand relationships and evolution within core Caryophyllales. Even if only some of the new placements mentioned below are confirmed - and confirmation is badly needed - character evolution may be affected, and clarifying the basic phytochemical, morphological, anatomical and embryological variation of the migratory taxa is essential.

It seems unlikely that the presence of betalains is plesiomorphic (Brockington et al. 2011; c.f. Cuénoud et al. 2002; Cuénoud 2002a; see also Clement & Mabry 1996). Both anthocyanin and betalain synthesis may have been acquired, lost, or flipped from one to the other more than once, the exact pattern of gains/losses/transitions depending on the optimisation procedure followed (Brockington et al. 2011). For betalain synthesis, see Gandía-Herrero and García-Carmona (2013) and for betalains as possible defence against herbivory, etc, see Berardi et al. (2013).

Other features with rather spotty distributions are anatomical. These include the presence of wide-band tracheids. Here the cells have narrow lumina because of the height of the wall thickenings, and are found in more or less desert-dwelling members of the [[Lophiocarpaceae [Hypertelis [Barbeuiaceae [Aizoaceae [Gisekiaceae [[Sarcobataceae + Phytolaccaceae] [Rivinaceae + Nyctaginaceae]]]]]]] [Molluginaceae [Montiaceae [[Halophytaceae [Didiereaceae + Basellaceae]] [Talinaceae [Anacampserotaceae [Portulacaceae + Cactaceae]]]]]]] clade (see below. The vascular anatomy of the lamina is quite often three-dimensional, with a ring of vascular bundles (peripheral vascular bundles) surrounding the midrib and which have the xylem either internal (endoscopic) or external (exoscopic), or the leaf is more or less flattened and the orientation of the vascular bundles is normal (Ogburn & Edwards 2013; Melo-de-Pinna et al. 2014). These features are connected with the succulence, shape and photosynthetic pathway of the leaf. Such leaves are particularly common in Chenopodioideae, Aizoaceae and Portulacinae.

There is considerable variation in the details of timing/pattern of intiation of both the perianth and androecial members, and some may be of phylogenetic interest (Ronse de Craene 2013: much information). The evolution of corolla-like structures ("C"/"petals" below) is not simple (see Ronse de Craene 2010 for numerous floral diagrams of this group, esp. 2012 and 2013). Any "corolla" present, as in
Caryophyllaceae, is usually described as being of staminal origin (e.g. Ronse
Decraene & Smets 1993; Leins et al. 2001), although Greenberg and Donoghue (2011) noted that it was perhaps surprising that such apparently staminodial petals in Caryophyllaceae are found in a clade in which stamen number is supposed to have increased from 5 to 10 irrespective of the presence/absence of staminodes: Caryophyllaceae with 5 stamens only rarely have petals (but c.f. Ronse de Craene 2013). In a number of taxa, including Dianthus, there appear to be two pairs of bracetoles below the flower, and these are sometimes described as an epicalyx. When there is a single perianth whorl, perhaps equivalent to the "calyx" of some Caryophyllaceae, this is quite often attractive and corolline, bracteoles then often being functionally calycine and borne immediately under the perianth. "Petals" may have evolved pehaps nine times or so in the clade and in a variety of ways (Brockington et al. 2009; see also Ronse de Craene & Brockington 2013; Ronse de Craene 2013). Brockington et al. (2012) showed that although the numerous "petals" of Aizoaceae-Ruschioideae and -Mesembryanthemoideae were of probable staminal origin, and the sepals of Sesuvioideae, for example, were also petal-like in part, B-class genes (AP3, PI) were not involved in their development (c.f. Ronse de Craene 2013), and they suggested that this might be the case throughout the core Caryophyllales.

When the stamens
are equal in number to the perianth members they are usually opposite to them. When
there are many stamens the initial primordia may alternate with the perianth members
(Aizoaceae) or continue the spiral of the perianth (Pereskia - Cactaceae, Leins & Erbar 1994a, b:
there may not be a perianth here); development is often centrifugal (see also Ronse de Craene et 2013).

Ovule number is also very labile. Thus a single ovule/gynoecium condition could be a synapomorphy for all Core Caryophyllales minus Macarthuria, but two or more ovules/gynoecium would have evolved more than once, and the single ovule condition regained. The whole clade (Rhabdodendraceae on up) could be characterized by its low ovule number, but, as mentioned elsewhere, Rhabdodendraceae and members of the next four pectinations are poorly known.

Ecology & Physiology. Taxa growing in saline and/or dry conditions are noticeably well represented here, and taxa that can grow on gypsum (hydrous calcium sulphate) are scattered throughout the clade (Douglas & Manos 2007). Such habitats are not ideal for mycorrhizal fungi, and they are not often reported from any Caryophyllales at all (but see Newman & Reddell 1987). Succulents are common, and many taxa have C4 photosynthesis, CAM, whether obligate or facultative, or their variants or precursors (Ehleringer et al. 1997; Sage et al. 2012, 2014; Winter & Holttum 2014; see also Ocampo & Colombus 2010; Christin et al. 2011b for dates); the PEPC enzymes involved in both C4 and CAM photosynthesis are members of the ppc-1E1 family (Christin et al. 2014b). Outside Poales, C4 photosynthesis is most common in core Caryophyllales, indeed, there are about one half (33/62) of all evolutionary origins of the syndrome in angiosperms here (Sage et al. 2011). See also Sage et al. (1999), Muhaidat et al. (2007 and references) and Christin and Osborne (2014) for the C4 pathway.

Robert et al. (2011) note that woody taxa with successive cambia often (86% of cases, lianes/vines not included) grow in conditions in which there is some kind of water stress. They noted that in at least some core Caryophyllales both xylem and phloem are organized to form a three-dimensional network.

Bacterial/Fungal Associations. A white blister rust, Wilsoniana, an oomycete, is found parasitic on taxa scattered throughout this clade (Thines & Voglmayr 2009 and references).

Chemistry, Morphology, etc. Details of betalain synthesis are poorly known, although tyrosine is the starting point; after modification to betalamic acid, it forms the chromophore for both betacyanins and betaxanthins, reddish and yellowish pigments respectively, the former acquiring another modified tyrosine unit (Tanaka et al. 2008; Pichersky & Lewinsohn 2011; Gandía-Herrero & García-Carmona 2013). The differences between betalain and anthocyanin synthesis pathways may not be that great (Strack et al. 2003; Shimada et al. 2007), complicating the issue, Shimada et al. (2005) found that anthocyanidin synthase genes were expressed in the seeds of both Phytolacca and Spinacia. For tannin (both classes) distribution, see Mole (1993). Sterol composition may be of systematic interest (Wolfe et al. 1989; Patterson & Xu 1990), with distinctive sterols common or dominant in Caryophyllaceae, Phytolaccaceae, Amaranthaceae, and "Portulacaceae". Isoflavonoids (Reynaud et al. 2005), sometimes quite diverse, and phytoecdysones are scattered in the Core Caryophyllales, but perhaps not in the Cactaceae area. For unlignified cell wall fluorescence, seeHartley and Harris (1981). Diferulic and p-coumaric acids are less commonly involved than in monocots, and alsthough sampling was quite extensive, neither the first two clades in core Caryophyllales nor members of the three clades basalo to them were investigated.

Stomatal morphology is variable,
but anomocytic stomata are common in nearly all families. However, in
Cactaceae and relatives, parallelocytic and other kinds of stomata are found; some families in this area have predominantly paracytic stomata. Stomatal orientation on stem and/or leaf is commonly transverse throughout the order (Butterfass 1987, Amaranthaceae s. str.?), however, it is unlear which taxa have vertically or which unoriented stomata. Variation in structures associated with the leaf base, whether hairs/colleters or "stipules", is considerable (Rutishauser 1981) and would repay further study; note that the basic nodal anatomy of the clade is one trace-one gap, unusual for plants with stipules as commonly accepted.

For a good general survey of floral morphology, see Hofmann (1994). Sepals with an abaxial crest are described from Caryophyllaceae, Amaranthaceae, Aizoaceae, and Portulacaceae (Ronse de Craene & Brockington 2013). If there is a "corolla", it develops at the same time or after the androecium,
not before it, and the "petals" and stamen(s) opposite them may form a
developmental unit (e.g. Eichler 1875; Wagner & Harris 2000). The corona - in Lychnis viscaria, at least - arises from two bulges on the adaxial side of the "corolla", perhaps representing anther thecae.

The carpels are quite commonly open in development, as also in Polygonaceae (Tucker & Kantz 2001). Placentation is quite variable, although one commonly thinks of this group as typically having free-central placentation or its variants. A subepidermal layer of cells in the inside of the ovary wall may have calcium oxalate sand, as in some Amaranthaceae and Polygonaceae, while in Nyctaginaceae a ring of cells immediately below the ovary havs conspicuous raphides (Guéguen 1901); there is little information on this feature. The integuments are often separated by a small space at their bases, but this seems to vary within Portulacaceae and Cayophyllaceae, and the space may be absent in Phytolacca and Amaranthaceae (e.g. Meunier 1890; Hakki 1973; c.f. Bittrich 1993). The apical cells of the nucellus are commonly elongated radially, as in Cactaceae, "Portulacaceae", Aizoaceae, Phytolaccaceae, and Amaranthaceae (see Johri et al. 1992; also Narayana 1962: e.g. Aizoaceae, Gisekiaceae, Molluginaceae), i.e., they form a nucellar pad, but it is unclear if this feature is of systematic significance. This seems to vary within Portulaca and Mesembryanthemum and there may be confusion with radially elongated and periclinally divided nucellar epidermal cells, which would represent a nucellar cap (Meunier 1980). There are often short hairs on the funicle that are directed towards the micropyle (Neumann 1935).

Seeds of a number of taxa have an operculum, although not necessarily identical in morphology (Bittrich & Ihlenfeldt 1984). There are commonly bar-like thickenings on the walls of the endotegmic cells (e.g. Netolitsky 1926; Bittrich 1993a; perhaps shown in Narayana 1962a), although these are absent from most Caryophyllaceae, at least - a detailed survey would be useful. Zheng et al. (2010) note that the starchy perisperm tissue is formed not from the parietal tissue surrounding the embryo sac, but from tissue immediately below the embryo sac, i.e., it is technically chalazosperm. For the loss of the intron of the rpl2 gene, see Logacheva et al. (2008).

Phylogeny. Understanding where taxa from the old Phytolaccaceae and Molluginaceae, both polyphyletic, are to be placed in the tree is critical for our understanding of relationships and evolution in core Caryophyllales. [Amaranthaceae [Achatocarpaceae +
Caryophyllaceae]] were early found to form a moderately well supported clade, the rest of the core
Caryophyllales another (Källersjö et al. 1998), however, although 13 families
were included in this study, sampling within them was poor. Similar relationships were suggested by Savolainen et al. (2000a). D. Soltis et al. (2000) found that Phytolaccaceae, Nyctaginaceae and Delosperma
(Aizoaceae) formed a group, also [Amaranthaceae + Caryophyllaceae], but again
the sampling was very sparse; for the position of Achatocarpaceae, see also Müller and Borsch (2005). For
other ideas of relationships, see Rodman (1994) and Downie and Palmer (1994: structural variation in chloroplast DNA).

Many of the relationships in the tree here are similar to those shown by Cuénoud et al. (2002: the Delosperma sequence was excluded, sampling still a bit sketchy), and these in turn are largely similar to relationships found by Källersjö et al. (1998) and other workers. Cuénoud et al. (2002) found two quite well supported clades within core Caryophyllales. There have been recent improvements in our understanding of relationships along the backbone of core Caryophyllales. Schäferhoff et al. (2009) found that the poorly-known Microtea, one of whose previous resting places was Phytolaccaceae, was sister to the rest of core Caryophyllales, but in a more recent study, Macarthuria, previously included in Limeaceae (and before that in Molluginaceae), occupied that position, and with strong support (Christin et al. 2011a: Microtea not included); Limeum itself (as the monogeneric Limeaceae) remained in its old position well embedded in core Caryophyllales.

Aizoaceae were monophyletic, albeit with only slightly better than marginal (52% bootstrap) support in an analysis of matK sequences, the only gene for which they had moderately good sampling; Gisekia moved position in analyses of rbcL sequences; and Sarcobatus was sister to Nyctaginaceae, albeit with only weak support, in matK analyses, while in a rbcL analysis it grouped with Agdestis (Cuénoud et al. 2002). Corbichonia (Lophiocarpaceae) and most of Hypertelis (one species was previously in Molluginaceae) were well supported as successive sister clades at the base of the [Aizoaceae [Gisekiaceae [Sarcobataceae, Phytolaccaceae, Nyctaginaceae]]] clade (Christin et al. 2011a); Hypertelis was also found to be in this general area of the tree in Schäferhoff et al. (2009: included only in their petD analysis). Here both Macarthuria and Hypertelis are placed separately on the tree (see also Brockington et al. 2011), although it is not clear exactly what the support values for these positions are. Arakaki et al. (2011) found that Gisekiaceae and Aizoaceae reversed positions, but with little support; that area was not the focus of their study. There is further discussion on relationships in the Gisekiaceae to Nyctaginaceae area below.

Relationships around Cactaceae, themselves a monophyletic group, remained difficult, and although progress has recently been made here (Brockington et al. 2009; Nyffeler & Eggli 2009; Ocampo & Columbus 2010; Soltis et al. 2011), some relationships still remain uncertain. However, Arakaki et al. (2011: see below) produced a largely resolved tree of that area.

Other relationships have been suggested, but sampling is usually poor, support poor, or the markers are unreliable. Thus Harbaugh et al. (2010) found that Molluginaceae were sister to Caryophyllaceae, rather than Amaranthaceae, although two taxa
from both families were all that were included in their study, which focused on Caryophyllaceae. Stegnospermataceae were sister to all other core Caryophyllales (support quite strong) and Limeum was placed with Amaranthaceae (support also quite strong) in a mitochondrial analysis by Qiu et al. (2010); however, Caryophyllaceae were not included. Support for the grouping [Stegnospermataceae [Caryophyllaceae + Amaranthaceae]] was found by Moore et al. (2011). Crawley and Hilu (2012) examined the effect of missing data and missing taxa on phylogenetic reconstructions here. Later they obtained trees that differ in several details from the one here, but support values were mostly low (see Crawley & Hilu 2013). Thus there were clades [Achatocarpaceae + Amaranthaceae] and [Stegnospermaceae + Limeaceae] or Stegnospermaceae were sister to all other core Caryophyllales examined and Limeaceae were in about the same position as in the tree above, etc..

Previous Relationships. Most of this group was included in
the old Centrospermae (so named because of the basal or free-central placentation that is common in the clade) or Caryophyllales in the strict sense. The shikimic acid pathway, particularly phenylalanine, is a starting point for the synthesis of nitrogen-containing benzylisoquinoline alkaloids and the betalains of core Caryophyllales, and Kubitzki (1994) suggested a relationship between core Caryophyllales, Magnoliidae and monocots because all contained such compounds.

Plants of Macarthuria are often rather rigid and rush-like shrubs with reduced leaves; the small flowers are distinctive in having five calycine perianth members, sometimes also five "petals", and eight stamens distinctly fused at the base.

Chemistry, Morphology, etc. For phytoecdysteroids, see Báthori et al. (1987), Dinan et al. (1998), and Zibareva et al. (2003). Mickesell (1990) listed both Amaranthaceae and Caryophyllaceae as having endosperm haustoria. Sukhorukov (2007) described the exotegmic cells of Chenopodiaceae s. str. as often having tannin deposits in the outer walls of the exotegmic cells that projected into the cell lumen (see also Kadereit et al. 2010).

Since Achatocarpaceae are poorly known, most of the features mentioned above as possibly characterising the clade need to be confirmed.

Caryophyllaceae are mostly herbs with
opposite, entire leaves that often have little in the way of a petiole and are
joined by a line at the base; geotropic adjustments occur at the swollen
nodes. The inflorescence is cymose and
the flowers often appear to have a clearly distinguishable calyx and corolla, the
latter being bilobed and/or clawed; there are usually 5 or 10 stamens. The fruit is often a capsule. Note, however, that petals may be absent and the fruit indehiscent and single seeded, the calyx can be very scarious, as
in Brachystelma, so like Amaranthaceae, while herbaceous Amaranthaceae also often have swollen nodes
and opposite leaves...

Age. The earliest fossils associated with Caryophyllaceae seem to be of the pollen Periporopollenites polyoratus, from the Late Campanian ca 73 m.y.a.. This has been linked with the macrofossil Caryophylliflora paleogenica from the Eocene of Tasmania, but these fossils cannot be identified as any known member of the family (Jordan & McPhail 2003).

Evolution.Divergence & Distribution. The diversification rate in European Dianthus is suprisingly high, 2.2-7.6 species/m.y. and (at the time) the highest rate recorded for either plants or terrestrial vertebrates (Valente et al. 2010a). The genus is summer-flowering (i.e. it flowers during the dry season) and contains many narrow endemics (Valente et al. 2010a). Relatives of Schiedia, which forms a substantial radiation on Hawaii, appear to include Honckenya and co., from the Arctic and subarctic (Harbaugh et al. 2009a).

For optimisation of characters in the context of a well-sampled phylogeny, see Greenberg and Donoghue (2011, but c.f. Fig. 5c).

Pollination Biology & Seed Dispersal. There is an association between some species of Silene and its relatives and Hadena, a noctuid moth; adult Hadena lays eggs on the ovary, its larvae eating at least some of the seeds, but it is also a pollinator - this is an obligate relationship for Hadena, rather like the yucca-yucca moth association (Kephart et al. 2006 for literature, see also other papers in that issue of the New Phytologist [169(4). 2006]). Flowers are also pollinated by other moths whose caterpillars do not eat ovules or seeds (Kula et al. 2013). See also Saxifragaceae, Phyllanthaceae, and Asparagaceae-Agavoideae for similar relationships.

Bacterial/Fungal Associations. Ectomycorrhizae have been reported from the family (Wang & Qiu 2006), while Newsham et al. (2009) noted the frequency of arbuscular mycorrhizae in polar Caryophyllaceae. For anther smut fungi, see Ngugi and Scherm (2006). Microbotryum violaceum s.l. (Uredinomycota - see also Montiaceae) is common on the family, especially on perennial Sileneae (ca 80% of the species), but not much on the annuals nor on members of the old Paronychioideae; strict cospeciation is not involved (Refrégier et al. 2008; Mena-Ali et al. 2009; Hood et al. 2010).

Genes & Genomes. There has been a massive increase in the rate of synonymous substitutions in the mitochondrial genome of Silene noctiflora, but not in that of the chloroplast genome, nor in the substitution rates of its immediate relatives (Mower et al. 2007). The mitochondrial genome of its relative, S. conica, is at 11.9 mb bigger than the whole nuclear genome of some eukaryotes, while S. latfolia has quite a small mitochondrial genome of only 0.25 mb. Species of Silene with such huge mitochondrial genomes may have over a hundred micro-chromosomes, as least from the evidence of the mapping procedures used (Sloan et al. 2012). At the same time, there are greatly accelerated rates of changes in the mutation rates of some genes, the position of the IR boundary, and various structural changes in the chloroplast genome of some species of Silene, and similar changes seem to have occurred in parallel (Sloan et al. 2014).

For the evolution of dioecy in Silene, which happened three times or so, see Desfeux et al. (1996) and Zluvova et al. (2008). Species of Silene subgenus Elisanthe have
an X-Y 'sex' determination system (Lebel-Hardenack et al. 2002; Charlesworth 2008 and references).

Chemistry, Morphology, etc. Variation in stipule morphology in Caryophyllaceae is considerable, even during the course of development of a single plant, as in Paronychia argentea (Rutishauser 1981).

In Pseudostellaria, at least, the stamens are initiated before the corolla (Luo et al. 2012). The long, curved nectary in some species of Schiedia develops on the abaxial bases of the stamens opposite to the calyx (Wagner & Harris 2000; esp. Harris et al. 2012). Weberling (1989 and references, esp. Thompson 1942) discusses placentation, which varies from axile, as in some species of Silene, perhaps the common condition in the family, to free central to the single, basal ovule of Uebelinia (this latter looks rather like a circinotropous basal ovule). A "chalazal" haustorium or diverticulum develops on the inside of the curved embryo sac in many species and the nucellus in Agrostemma is massively thick (Rocén 1927). Members of the old Paronychioideae in particular have solanad rather than
caryophyllad embryo development.

Some general information is taken from Bittrich
(1993b) and McNeill (1962: the old Alsinoideae, also maps), for chemistry, see Hegnauer (1964, 1989), for the distribution of phytoecdysteroids, see Zibareva et al. (2003) and cyclopeptides, see Jia et al. (2004), for stomata, see Rohweder et al. (1971: correlation between stomatal apparatus and leaf width), for stem anatomy, see Schweingruber (2007), for floral morphology, etc., see Thompson (1942), Rohweder (1967b, 1970a), Rohweder and Urmi-König (1975) and Rohweder and Urmi (1978), for stamens or nectaries as corolla, see Mattfeld (1938) and Leins et al. (2001), for ovules and seeds, see Meunier (1890) and for much information on ovules and early embryogenesis, see Rocén (1927), also Cook (1909), Perotti (1913).

Phylogeny. Of the old subfamilies, Paronychioideae - classically defined by the presence of stipules, lack of a corolla, and utricular fruit - form a basal grade, with Corrigioleae (Telephium, Corrigola) sister to all the rest of the family. Dicheranthus, Polycarpon, etc., may form the next clade, Paronychia, etc., the next. Drymaria and Pycnophyllum, both morphologically distinctive taxa, may be sister (Smissen et al. 2002 - they noted that Pycnophyllum [and Pentastemonodiscus] were not to be included in Caryophyllaceae-Alsinoideae, but they did not suggest where they should go; Fior et al. 2006). In the erstwhile Alsinoideae the calyx is free and the corolla has ± open
venation. Alsinoideae for the most part break down into two groups: one, including Cerastium, Stellaria, etc., has capsules with split valves, and the other, including much of Minuartia, Sagina, etc., is very diverse, but has capsules with entire valves; the corolla is often bilobed. In a recent comprehensive study of Minuartia (Sagineae), Dillenberger and Kadereit (2014) demostrate is extensive polyphyly. For Moehringia (Arenarieae), the evolution of its strophiole, and its allies, see Fior and Karis (2007 and references). Finally, Caryophylloideae, with their connate calyx and a clawed corolla
with more or less closed venation and adaxial appendages (ligules), are holding up better phylogenetically. The tribes Sileneae and Caryophylleae are perhaps monophyletic, and together are sister to or form a polytomy with part of Arenaria (Nepokroeff et al. 2002; Fior et al. 2006).

Relationships in Harbaugh et al. (2010) - on the whole well supported - from a three-gene analysis are [Corrigolieae [Paronychieae [Polycarpeae [Sperguleae [[Sclerantheae + Sagineae] [[Arenarieae + Alsineae] [Sileneae [Caryophylleae + Eremogeneae]]]]]]]]. Greenberg and Donoghue (2011) sampled more extensively but found a largely similar topology; a novel clade that they found, [[Sclerantheae + Sagineae] [[Arenarieae + Alsineae]], did not have much support. The position of the newly described Eremegoneae was uncertain in Harbaugh et al. (2010), but support was stronger in Greenberg and Donoghue (2011); in its current position its apomorphies are losses of the apomorphies of the whole [Sileneae [Caryophylleae + Eremogeneae]] clade, or, alternatively, these features arise independently in Sileneae and Caryophylleae... Within Sagineae, Drypis, previously in Caryophylloideae because its connate calyx, etc., is in the same immediate clade as Habrosia (ex Alsinoideae), so the variation there is considerable (Harbaugh et al. 2010; see also Greenberg & Donoghue 2011). The phylogenetic structure now evident in the family has considerable implications for character evolution - see Greenberg and Donoghue (2011) in particular.

Pirani et al. (2014) discuss the phylogeny of Acanthophyllum (Caryophylleae), and for the phylogeny of Dianthus in Eurasia, see Valente et al. (2010a). For the phylogeny of Silene and its relatives (Sileneae), perhaps not monophyletic, see Desfeux and Lejeune (1996) and Erixon and Oxelman (2008), and for that of Viscaria, etc., see Frajman et al. (2009).

Classification. The old tripartite division of the family into Silenoideae, Alsinoideae and Paronychioideae based on presence of a hypanthium, whether or not the petals were emarginate, whether the calyx was fused or not, etc., is not confirmed by recent work. Here I follow the tribal classification of Harbaugh et al. (2010, see also 2012: ?Drypidae Fenzl?). These authors did not sample a number of genera, so tribal compositions were uncertain, but the situation was considerably improved by Greenberg and Donoghue (2011). The tribal implications of the study by Dillenberger and Kadereit (2014) are unclear.

Features like number of styles and whether there is obviously a common stylar region often provided generic characters in the past, yet they turn out to be of little use (e.g. Dillenberger & Kadereit 2014). Thus the limits of Silene, historically characterised by having three styles, need to be expanded to include some taxa with five styles (Desfeux & Lejeune 1996). Genera like Arenaria and Minuartia are polphyletic (Harbaugh et al. 2009); indeed, many generic limits need attention (Greenberg & Donoghue 2011). Dillenberger and Kadereit (2014) have dismembered Minuartia, necessary because the genus in its old, broad circumscription was hopelessly polyphyletic.

Botanical Trivia. There are reports of placental tissue from 30,000 year old material of Silene stenophylla (or perhaps from another species of the genus) trapped in permaforst being persuaded to form whole plants (Yashina et al. 2012a, b).

Age. The age of crown-group Betoideae is about 48.6-35.4 (including Acroglochin) or 38.4-27.5 (excluding it) m.y. (Hohmann et al. 2006).

Synonymy: Betaceae Burnett

Amaranths are usually herbs and are commonest in tropical areas. The perianth is chaffy and coloured in flower, the stamens are basally fused and often with staminode-like structures; the fruit usually is a circumscissile capsule.

Chenopods are more or less succulent herbs often
with swollen nodes; they prefer dry and/or saline and temperate to subtropical habitats. The small flowers
have a greenish perianth that often becomes variously elaborated after flowering and surrounds the usually indehiscent fruits.

Evolution.Divergence & Distribution. Chenopodioideae s.l. probably originated in Eurasia, perhaps in environments close to the shore, with subsequent movement around the northern hemisphere and then into the southern hemisphere (e.g. Hohmann et al. 2006; G. Kadereit et al. 2010, 2012). For instance, there have been some nine invasions of Australia, mostly since the late Miocene so within the last 10 m.y. (Kadereit et al. 2005), and there have probably been two invasions by C4Atriplex into North America and then to South America, and two invasions of Australia (Kadereit et al. 2010). Atriplex radiated in Australia in and after the late Miocene (Prideaux et al. 2009; Kadereit et al. 2010); evolution of the C4 clade in the New World probably started a little earlier. Within Betoideae, California-Mediterranean disjunctions have been dated to 15.4-8.1 m.y.a., perhaps via Beringia (Hohmann et al. 2006).

Ecology & Physiology. Amaranthaceae include some 500 species with the C4 photosynthetic syndrome, fully one third of all BLA C4species (Osmond et al. 1980; Sage et al. 2012). The literature is extensive, and I have not done it justice, but the references below should serve as an entrance. There are several types of C4 photosynthesis and ca 17 different kinds of leaf anatomy, not all C4, in the family (e.g. Edwards & Voznesenskaya 2011; Freitag & Kadereit 2014). For summary comparisons of the chloroplast types of C3 and C4 taxa, see Koteyeva et al. (2011b), and for comparisons of two C4 species, see Koteyeva et al. (2011c).

There have been 15 or more independent acquistions of the C4 pathway, perhaps with reversals (e.g. Pyankov et al. 2001; Kadereit et al. 2012). Two thirds of these acquisitions are in the old Chenopodiaceae (Akhani et al. 1997; Pyankov et al. 2001; Kadereit et al. 2003, 2012; Sage et al. 2007, 2011; Kadereit & Freitag 2011). The first acquisition of C4 photosynthesis in Amaranthaceae can be dated to the early Miocene ca 24 m.y.a., the age of a major C4 clade in Atriplex can be dated to 14.1-10.9 m.y., and other acquisitions may be a quarter of that age or less (Kadereit et al. 2003; Kadereit et al. 2010; Kadereit & Freitag 2011: Christin et al. 2011b for many dates), however, Kadereit et al. (2012) estimated that the first acquisition was a little earlier (47-22 m.y.a.) at the Eocene/Oligocene boundary. There has been a single origin of C4 photosynthesis within North American Atripliceae, Atriplex s. str. (Zacharias & Baldwin 2010). For parallel evolution of C4 leaf types in Camphorosmeae, see Kadereit et al. (2014).

Voznesenskaya et. al. (2013) discuss in detail transitions between photosynthetic types in the predominantly C4 Salsoleae. For the evolution of enzymes involved in C4 photosynthesis in Alternanthera, where there are also C2 intermediates, see Gowik et al. (2006); C4 photosynthesis seems to have originated once here (Sánchez del-Pino et al. 2012). Rosnow et al. (2014b) noted that different amino acids were to be found in Suaedoideae in a position thought to be critical in determining affinity for phospoenolpyruvate in the carboxylase enzyme.

In at least four Suaedeae s.l. all the different elements of C4 photosynthesis are to be found within a single cell, and although there is no conventional Kranz anatomy, the chloroplasts involved in different parts of the carbon fixation process are distinct and spatially segregated; this condition has evolved independently at least twice (Kapralov et al. 2006: Bienertia, Suaeda). Partitioning of the plastids within the cell is maintained by the distinctive organization of the cytoskeleton (Chuong et al. 2006), although plasticity is induced by the light environment (Lara et al. 2008). The different plastids in Beinertia may be either proximal and distal (with respect to adjacent veins) in elongated cells, or peripheral and central, the latter domain including most chloroplasts and being where the C3 part of the pathway occurs (Offerman et al. 2011); Rosnow et al. (2014a) explore how the chloroplasts differentiate.

Many succulent chenopod C4 halophytes grow in the Irano-Turanian region (Ogburn & Edwards 2010) and they make up a major element of the vegetation there. In the rather cold Gobi deserts 15-17% of the species are C4 plants (they are only 3.5% of the total Mongolian flora), and they contribute 30-90% of the biomass there (Vostokova et al. 1995; Pyankov et al. 2000). Over 50% of the total C4 flora in the Gobi Desert is made up of fast-growing C4 chenopods (there are also some Polygonaceae), some of which are arborescent. A similar combination of plants also dominates the halophytic vegetation of the Central Asian Turanian deserts (Winter 1981); these are somewhat warmer than the Gobi deserts. Some of these C4 plants get quite large, Haloxylon aphyllum (Amaranthaceae) attaining 10 m in height and with a trunk 1 m across (Winter 1981). Succulent C3 chenopods are common in the Gobi in true desert conditions, and also in moist, saline soils (Pyankov et al. 2000).

There are ca 380 halophytic species of chenopods in particular, the largest concentration of halophytes in flowering plants. A number of these, ca 43%, are also C4 plants (Jacobs 2001; Sage 2002; Flowers & Colmer 2008). Kadereit et al. (2012) also noted the connection between C4 photosynthesis and salt tolerance. Chenopods in general are most diverse in deserts from Sahara to Central Asia. Adaptations to salt tolerance, involving succulence and also drought tolerance, may have first appeared in coastal plants of Eurasia in the Eocene and have later facilitated the subsequent adoption of C4 photosynthesis. However, compared with grasses, there are relatively few origins of salt tolerance (Kadereit et al. 2012; Bennett et al. 2013).

Chenopods are very diverse in Australia, with 279 species (as of 2004) endemic there (Kadereit et al. 2004). Aridification in Australia began early in the Miocene ca 22 m.y.a., and almost 150 species of shrubby drought- and salt-tolerant - and C3 - Camphorosmeae radiated there ca 7.5 m.y.a. (Kadereit et al. 2004; Kadereit & Freitag 2011; Cabrera et al. 2012 for numerous dates; Freitag & Kadereit 2014). C4 taxa like Atriplex also diversified in Australia and was probably a major item in the food of the extinct giant (ca 230 kg) kangaroo Procoptodon goliah (Prideaux et al. 2009; Kadereit et al. 2010). See also Clade Asymmetries.

Plant/Animal Interactions. Cecidomyiid midges (Asphondylia) form galls on chenopods like Sarcocornia and Tecticornia in Australia; fungi also live in the galls, although the relationshp between the fungi and the midge larvae (the former are food for the latter?) is unclear (Teresa Lebel, pers. comm.).

Bacterial/Fungal Associations. Although the family is apparently largely without mycorrhizae, vesicular-arbuscular mycorrhizae have been reported from chenopods in the Red Desert of Wyoming - but only on native taxa and under undisturbed conditions (Miller 1979); c.f. also Zygophyllaceae.

Chemistry, Morphology, etc.Polycnemum and Nitrophila have ben reported to have ordinary secondary thickening, but c.f. Heklau et al. (2012) and Masson and Kadereit (2013). For a discussion about the cortical vascular system and leaves of Salicornia and relatives, see Fahn and Arzee (1959), James and Kyhos (1961) and Beck et al. (1982). Stem collenchyma is well
developed; there are nucleated xylem fibres (Rajput 2002). Stem-borne roots of Polycnemum seem to have a superficial cork cambium (Heklau et al. 2012).

The flowers of Chenopodioideae s.l. show a considerable amount of variation, partly because of the involvement of the perianth in fruit dispersal, and partly because the flowers may be quite reduced. In the reduced perianth of the Australian Tecticornia (Salicornioideae) the odd member is abaxial (for floral development, see Shepherd et al. 2005b). The flowers of Beta become semi-inferior during development (Flores-Olvera et al. 2008) and the "bracteoles" enveloping the flower and fruit in some Atripliceae are modified perianth members (Flores-Olvera et al. 2011).

Pollen of Amaranthaceae (inc. Chenopodiaceae) is fairly homogeneous
(Nowicke 1975; Skvarla & Nowicke 1976), both having a similarly thickened tectum, apertures with reduced pointed flecks of exine underlain by lamellar plates, and a thickened endexine; Pseudoplantago has cuboid pollen. However, there is quite a bit of variation beyond this (e.g. Borsch 1998; Borsch & Barthlott 1998). Müller and Borsch (2006c) discuss the evolution of the distinctive stellate pore ornamentation of the pollen of some Amaranthaceae s. str. - there are several independent gains and losses.

2-carpellate members of the
family usually have collateral carpels, but occasionally they are superposed. The chalazal region of the ovule is more or less digested by the embryo sac in at least some Amaranthaceae - and this is also once recorded from Nyctaginaceae (Maheshwari 1950).

Phylogeny. Cuénoud et al. (2002) found Amaranthaceae s. str. to be monophyletic, with very strong (97%) support, and Chenopodiaceae s. str. were perhaps monophyletic, but the branch collapsed in a strict consensus tree; the sampling was moderately good, but only the matK gene was analysed. In an extensive rbcL analysis, much of the old Chenopodiaceae were again monophyletic, but with little bootstrap support, ditto the old Amaranthaceae (incl. Polycnemoideae), while Betoideae were paraphyletic (G. Kadereit et al. 2003). Other studies had suggested that Chenopodiaceae were paraphyletic and perhaps even that Amaranthaceae were polyphyletic (Pratt 2003; Pratt et al. 2001). In an analysis of matK/trnK sequences, Müller and Borsch (2005b, c) found that Polycnemum and Nitrophila (100% support) were sister to the rest. Masson and Kadereit (2013) provide a phylogeny of the subfamily. The clade [other Amaranthaceae + Chenopodiaceae] had <70% bootstrap support and still lower PP values, Amaranthaceae s. str. had 100% support and the Chenopodiaceae s. str. again <70% bootstrap support yet 1.0 PP..

Within Amaranthaceae s. str. - at least some flowers imperfect - Bosea and Charpentiera were successively sister to the rest, but Amaranthoideae, Amarantheae and Amarathineae were paraphyletic (e.g. Ogundipe & Chase 2009). Amaranthus is sister to Beta, etc., in ORF 2280
phylogenies, and this whole group is in turn sister to the [Celosia [(some Celosieae), Froelichia, etc. +
Gomphreneae/Gomphrenoideae]] clade (Cuénoud et al. (2002). For Gomphrenoideae, see Downie et al. (1997) and Sánchez del-Pino (2007). Within Gomphrenoideae are the iresinoids (Iresine should be circumscribed broadly), and the [gomphrenoids (Gomphrena is polyphyletic) + alternantheroids (Alternanthera is monophyletic)] (Sánchez del-Pino 2007; Sánchez del-Pino et al. 2009). The monophyly of Alternanthera has been confirmed (Sánchez del-Pino et al. 2012).

Relationships within the old Chenopodiaceae are having to be much reworked because the often highly reduced and modified flowers and fruits have been difficult to understand and interpret, hence leading to unsatisfactory taxon delimitations. Kadereit et al. (2010) examined relationships in Atripliceae, and Chenopodium as included there turned out to be polyphyletic. Relationships between Dysphanieae Pax (plant aromatic, with stalked or subsessile glands), Atripliceae Duby (inc. Chenopodieae), Axyrideae and Anserineae (inc. Spinacieae) are unclear, although the tribes seem to be monophyletic (Fuentes-Bazan et al. 2012b for a summary); Fuentes-Bazan et al. (2012a) found that Atriplex and other genera were nested within Chenopodium s.l. - in fact, members of four tribes were intermingled. For Atripliceae, see also Zacharias and Baldwin (2010: North American taxa).

Other studies on chenopodioids: see Schütze et al. (2003: Suaedoideae), G. Kadereit et al. (2005: Australian chenopods, 2006: Salicornioideae), and for relationships in the Australian Tecticornia (Salicornioideae) and its relatives, see Shepherd et al. (2004, 2005a). See Akhani et al. (2007) for Old World Salsoleae and Salsoloideae in general, Cabrera et al. (2009) looked at relationships in the Australian Camphorosmeae, and Kadereit and Freitag (2011) the Camphorosmoideae as a whole. Wen et al. (2010) found that Salsoleae s.l. were monophyletic. Hohmann et al. (2006), working on Betoideae, found that Acroglochin, with circumscissile capsules like other members of the subfamily, tended to wander around the tree; they did not place it.

Classification. For the classification of Suaedoideae, see Schütze et al. (2003), for that of Salicornioideae, see Kadereit et al. (2006), of Camphorosmoideae, Kadereit and Freitag (2011), of Salsoloideae, see Akhani et al. (2007), of Chenopodioideae, see Fuentes-Bazan et al. (2012b). However, a comprehensive classification of Amaranthaceae s.l. is badly needed.

Cabrera et al. (2009) found generic problems in the Australian Camphorosmeae, Maireana being in a particular mess. Zacharias and Baldwin (2010) divided the C3 North American Atriplex and relatives, which are quite variable, into a number of genera, while Fuentes-Bazan et al. (2012a, esp. b) made the needed nomenclatural changes for the dismemberment of Chenopodium s.l. into seven genera.

Within Gomphrenoideae, Iresine should be circumscribed broadly and Gomphrena is polyphyletic (Sánchez del-Pino 2007; Sánchez del-Pino et al. 2009). Some of the extreme halophytic genera are morphologically much modified, and generic limits are difficult. There is much variation in fruit and seed, the former in particular involving apparent adaptations for dispersal, and genera based on this variation are not holding up (Shepherd & Wilson 2007; Kadereit & Freitag 2011).

Stegnospermataceae are more or less scandent or sprawling
plants with rather fleshy leaves and racemose inflorescences that have petaloid flowers, the "corolla" being more or less
rotate.

Chemistry, Morphology, etc. Like Caryophyllaceae, there are
special cells in the wood that contain sphaerites; there is only diffuse axial xylem
parenchyma. There is no nucellar cap. Are the seeds endospermic?

Previous Relationships. Stegnospermaceae have often been included in Phytolaccaceae. The two look rather similar, and have a somewhat similar gynoecium, but they are most obviously distinguishable by their flowers which have
petals. They also have pollen with a
prominent foot layer and massive endexine - this is thin in
Phytolaccaceae. The ovules are
epitropous, while in pluricarpellate Phytolaccaceae they are apotropous (Rogers
1985).

Chemistry, Morphology, etc. The "petals"/petaloid staminodes are described as coming from the base of the outer stamens (Ronse de Craene 2013). The nature of the gynoecium is unclear, but there are certainly two stigmas and sometimes (at least) clearly two styles that are very close together at the base (e.g. Jeffrey 1961).

Evolution.Physiology & Ecology. Wide-band tracheid pith cells are scattered in
succulent members of this clade, e.g. Aizoaceae, Cactaceae, and Portulacaceae. They are also found in the leaf away from the midrib
in Aizoaceae; bands are narrow but very tall (= "wide"), so the cell lumen is locally very
narrow (Mauseth et al. 1995: similar in Hectorella [Montiaceae]; Carlquist 1998b). In a recent study of Ariocarpus fissuratus (Cactaceae), it was found that as the rays expanded these tracheids could contract, so allowing the whole root to contract, and the plant remained closer to the rocky ground where the temperatures were cooler (Garrett et al. 2010).

Chemistry, Morphology, etc. Limeaceae, Cactaceae and "Portulacaceae" have cells in rows along the dorsal junction of the seed.

Phylogeny.Corbichonia (Lophiocarpaceae) and most of Hypertelis (one species is in Molluginaceae) were well supported as successive sister clades at the base of this clade (Christin et al. 2011a). However, the whole clade badly needs study to establish relationships along its backbone; Aizoaceae and Nyctaginaceae seem to be the only fixed entities around here.

Chemistry, Morphology, etc. These two genera are florally very different, as is clear from the characterization above.

For Corbichonia flowers, see Ronse de Craene (2007), for embryology, see Narayana (1962a) and Narayana and Lodha (1963: as Orygia, ovules shown as almost anatropous), and seeds, see Hassan et al. (2005a). For some general information, see Adamson (1958) and Hofmann (1973).

Species of Hypertelis are small plants with tufted or subfasciculate linear and fleshy leaves with sheathing stipules; the infloresecence is pedunculate and appears subumbellate, the pedicellate flowers having three, sometimes four, petals and brightly coloured stigmas and anthers.

Chemistry, Morphology, etc. The inflorescence is interpreted as being terminal and cymose (Hoffmann 1973). In bud, the perianth members enclose the rest of the flower and are sepal-like; in the open flower three or four expand and are petal-like, and the anthers and stigmas are also brightly colored.

1-11/100. S. Africa, a few species also W. South
America, Australia, N. Africa, the Mediterranean and the Near East, naturalised in W. North America (map: see Fl. Austral. 4. 1984; Pascale Chesselet, pers. comm. 2004).

Aizoaceae are more or less prostrate herbs that may be
recognised by their fleshy, opposite leaves the bases of which are membranous and usually surround
the stem, and by the frequent occurrence of bladder-like epidermal cells. The flowers either have five perianth members that are green outside and
coloured inside or numerous linear "petals", much-modified stamens. There are usually many stamens, a more or less inferior and
septate ovary, and a fruit that opens on moistening as septal or other tissues swell.

Evolution.Divergence & Distribution. The "meganiche" dominated by the family in southern Africa - rather arid winter-rainfall areas with moderate temperatures - may be only some 5 m.y. old (Ihlenfeldt 1994a). Klak et al. (2004) suggested that the radiation in Ruschioideae in S.W. Africa, at least, was both recent (3.8-8.7 m.y.a.) and very fast, however, the estimates in Arakaki et al. (2011) are about twice as old, while those in Valente et al. (2014) are somewhat younger - and after the origin of the Greater Cape Floristic Region in which core Ruschioideae in particular are so common. Apatesieae and Dorotheantheae are successively sister to the remainder of Ruschioideae, they are not very speciose. The much more speciose core Ruschioideae often have crest-like (lophomorphic) nectaries and hygrochastic and sometimes long-persistent capsules with a distinctive anatomy (for which, see Kurzweil 2006) that release only a few seeds at a time (see above for other characters). Klak et al. (2013) discussed the phylogeny of Ruschieae in the context of adaptations to different rainfall regimes and geography in general. Kellner et al. (2011) looked at genetic differentiation in Lithops in the context of morphology and geography.

Ecology & Physiology. Aizoaceae, in particular Mesembryanthemoideae and Ruschioideae, dominate much of the Succulent Karoo of southwestern Africa, making up more than 50% of the species and up to an astounding 90% of the biomass. Members of these groups may be either salt-tolerant or drought-avoiders, and it is unusual to have this variation in quite closely related species (Ogburn & Edwards 2010). Edaphic specialization - soils can vary considerably locally - seems to be involved in the diversification of the family (Ellis & Weis 2006), and core Ruschioideae in particular flourish under such conditions (Valente et al. 2014). Although some work has been carried out on details of anatomy and cell micromorphology and possible links to ecophysiology (see Vegetative Variation below; Melo-de-Pinna et al. 2014), much more needs to be done.

C4 photosynthesis occurs in some members of this clade, especially Sesuvioideae (Sage et al. 1999); some origins may be as much as (27-)22.1(-17.2) m.y.a., others are much younger (Christin et al. 2011b). C3/CAM intermediates are also known, as in Mesembryanthemum crystallinum (Winter & Holtum 2014; see also Mioto et al. 2014).

Pollination Biology & Seed Dispersal. Aizoaceae in the drier areas of southwestern Africa are much visited by bees, which also visit Asteraceae there (Kuhlmann & Eardley 2012) - the two do have grossly similar flowers.

Straka (1955), Ihlenfeldt (1983) and Hartmann (1988) have described the intricate morphology of the capsules of the [Aizooideae [Mesembryanthemoideae + Ruschioideae]] clade, which are often hydrochastic. There are septal keels that reach from the central axis to the valve tips that expand when they absorb water. Seed dispersal is by "jet action" using the kinetic energy of falling raindrops (= ombro[hydro]chory: Parolin 2006; see also Kurzweil 2006), and how far the seeds are dispersed depends on the details of the capsule morphology. The ease of dispersal of the seeds is inversely correlated with the distance the seed travels - if easily ejected, the seeds are not propelled far, and in Ruschioideae only a few seeds at a time leave the capsule. In a few taxa mericarps are the units of dispersal. There is also considerable variation in the establishment "strategies" of the seeds. Many Sesuvioideae, with more conventional fruits, have arillate seeds and are myrmecochorous (Lengyel et al. 2009).

Vegetative Variation. Variation in characters such as leaf size and shape and internode elongation is considerable (Ihlenfeldt 1994a). Although species with foliaceous bracts or bracteoles in which the inflorescence is not distinct from the rest of the plant are sometimes distinguished from those with smaller bracts and distinct inflorescences (e.g. Hartmann 1993), it is unclear to me what the real growth characters are and where they go on the tree. A number of taxa have bladder-like cells on the leaf surface ("idioblasts") that may be involved with water uptake from dew or mist. Other taxa have an epidermis with massively-thickened outer cell walls that contain layers of calcium oxalate crystals (e.g. Ihlenfeldt & Hartmann 1982). In addition, individual cells may be variously papillate or the surface otherwise sculpted and/or with epicuticular waxes, the stomatal openings may be deeply sunken, etc. (e.g. Ihlenfeldt & Hartmann 1982; Hartmann 2002; Opel 2005a).

The leaves of many core Ruschioideae, i.e., not including Drosanthemeae and Ruschieae, are more or less flush with the surface of the ground; they can be almost invisible in the stony habitats in which they grow, being greyish or brownish and looking like pebbles except when they flower - hence "flowering stones". These leaves are prophylls or bracteoles, the flower is terminal, and renewal shoots, the next flowering units, develop in the axils of the prophylls (Hartmann 2004, 2006 for a summary). In some species of Conophytum the leaves are almost completely connate except for a slit across the top out of which the flower and next pair(s) of leaves appear.

The leaves of Mesembryathemoideae and core Ruschioideae are cylindrical or trigonous, not more or less flattened (Klak et al. 2004; Chesselet et al. 2004; Melo-de-Pinna et al. 2014), and there is a system of peripheral vascular bundle surrounding the more or less arcuate midrib (3D vascular tissue - see Ogburn & Edwards 2013); these vascular bundles have internal xylem, and it is as if the lamina had been abaxialized (Melo-de-Pinna et al. 2014). In core Ruschioideae the leaves lack the bladder-like epidermal cells of the rest of the family. The exposed surfaces of the leaves sometimes have distinctive "windows". In Lithops the window patterning may reflect venation reticulation or the position of huge, tannin-containing, subepidermal cells (Korn 2011). A duplication of the ARP gene, involved elsewhere in leaf development, is correlated with the diversification of core Ruschioideae, and it may be involved in the evolution of the diverse leaf morphologies of this group, although there is currently no more than a simple correlation on which to go (Illing et al. 2011, c.f. the phylogenetic interpretation there).

Chemistry, Morphology, etc. Studies of the wood anatomy of Aizooideae and Sesuvioideae are needed to clarify wood evolution there (Carlquist 2007a); see Rajput and Patil (2008) for a study of vascular development in Sesuvium portulacastrum. Melo-de-Pinna et al. (2014) note a possible correlation between expanded, more or less connate leaf bases and a system of peripheral vascular bundles in the blade which have internal xylem.

The petal-like basal part of the perianth (= sepals) in Sesuvioideae is equivalent to the sheathing vegetative leaf base while the apical "horn" represents the rest of the leaf, rather as in monocot leaf development (c.f. Vorlaüferspitze!). B-class floral genes were expressed neither in the petaloid basal part nor in the petal-like staminodes of Aizooideae and Ruschioideae (Brockington et al. 2012; for the latter c.f. in part Frohlich et al. 2007). The androecium may arise as a ring meristem or as five separate primordia.

Smets (1986) recorded the
presence of a receptacular nectary disc. Although Niesler and Hartmann (2007) suggested that the correlation of nectary morphology with major clades was not that strong, noting that the nectaries in Glottiphyllum (Ruschioideae) were more or less flat, they occur in (are restricted to? - see above) the two basal clades in that subfamily.

The nature of the inferior ovary may repay investigation. In Tetragonia, at least, flowers may develop in the axils of bracts on the outside of the ovary (Prakash 1967), rather like the situation in some Cactaceae. Hartmann (1993) recorded a nucellar cap in Aizoaceae, but by this he meant the radially elongated cells of the nucellar epidermis; Prakash (1967) perhaps implies there is a nucellar cap in Tetragonia; Cocucci (1961) noted that the radially elongated epidermal cells of the ovule divide anticlinally.

Phylogeny. I follow Klak et al. (2003) for basic groupings in the family; Aizoaceae s. str. (e.g. Chesselet et al. 1995) would seem to be paraphyletic. Tribulocarpus, which used to be in Tetragonioideae (for which, see Aizooideae), is sister to the other Sesuvioideae, in which it is included here (Klak et al. 2003; Thulin et al. 2012a); it has an indehiscent fruit and so hardly surprisingly lacks arillate seeds. For a phylogeny of Sesuvioideae, see Hassan et al. (2005b). Tetragonia is embedded in Aizooideae (Klak et al. 2003), however, it has wood rays, it lacks the bands of xylem fibres of other Aizoaceae, and there is vasicentric parenchyma adjacent to these fibres (Carlquist 2007).

Within Ruschioideae, Apatesieae and Dorotheantheae are successively sister to the remainder (see above for morphology, etc.; Klak & Bruyns 2012 for a phylogeny of Dorotheantheae). The remainder, core Ruschioideae, have also lost the chloroplast rpoC1 intron (Thiede et al. 2007) - c.f. Cactoideae. There is a detailed phylogeny of Ruschieae in Klak et al. (2013); see Opel (2005b) for a morphological phylogenetic analysis of Conophytum.

Classification. There is a combined [list] of genera recognised in Mesembryanthemoideae and Ruschioideae, but generic boundaries are uncertain. In the early twentieth century Mesembryanthemum included the whole of the Ruschioideae and Mesembryanthemoideae, and until recently Mesembryanthemoideae, much the smaller of the two subfamilies, was divided into numerous genera. However, Klak et al. (2007) in a comprehensive study of the subfamily, obtained quite detailed phylogenetic resolution within it. Mesembryanthemum itself, although quite a small genus, was polyphyletic, and any attempt to maintain current genera would, Klak thought, have caused the recognition of numerous and often poorly characterised taxa; only one genus was recognised. This decision may have to be revisited, since others think that clades there can be characterised (V. Bittrich, pers. comm.; Liede-Schumann & Hartmann 2009).

Klak et al. (2013) note that there are problems with generic limits in Ruschieae, and there are problems with species limits, too. Hammer in 1993 noted that there were then about 1,800 known populations of Conophytum (Ruschioideae) - for which there were 450 names; current estimates of species numbers for this genus range from 87 to 290. For a general account of Lithops, see Cole and Cole (2005). For an infrageneric classification of Drosanthemum, see Hartmann (2007).

Phylogeny. Relationships in this area are still somewhat unclear. Douglas and Manos (2007) found only moderate support for the monophyly of Nyctaginaceae and vanishing little support for the monophyly of Phytolaccaceae (including Sarcobataceae). Similar relationships were found by Brockington et al. (2009), but with Gisekia strongly supported as sister to the whole clade (see also Bissinger et al. 2014). Indeed, Giseckia has been thought to be "discordant" wherever it is put, and in some phylogenies it came out in or near Phytolaccaceae-Rivinioideae (see Cuénoud et al. 2002; Christin et al. 2011b), althouth this seems to be an unlikely position.

Rivinaceae and Nyctaginaceae have gynoecia made up of a single carpel (Cuénoud et al. 2002), and the carpels of Mirabilis and Rivinia do look remarkably similar to each other (Leins & Erbar 1994). If Sarcobataceae are placed somewhere around here their carpel number is a reversal.

Phytolaccaceae can be recognised by their racemose
inflorescences of apetalous flowers which have many, connate carpels each with a single basal ovule and a separate style; the fruit is often
a berry. The plants are herbs, trees,
or lianes, and the leaves tend to be rather thick and fleshy, lacking prominent
fine venation.

Evolution.Divergence & Distribution. Fossil fruits from the Upper Cretaceous (late Campanian) of Mexico are similar to those of Phytolacca, Cevallos-Ferriz et al. (2008) noting a palisade exotesta and also a palisade layer in the tegmen.

Chemistry, Morphology, etc.Petiveria and Gallesia smell of onions. Nowicke (1969) described some Rivinaceae as having "stipular thorns" up to 5 cm long; these are probably prophyllar.

Both Monococcus and Petiveria
have four perianth parts that are diagonally arranged but their bracteoles are strictly lateral, while the perianth of the other genera is orthogonally arranged and the bracteoles are slightly adaxial (e.g. Vanvinckenroye et al. 1997). Ovules of Petiveria have a nucellar beak.

Nyctaginaceae may be quite easily recognised. The family includes herbs with swollen nodes, as well as lianes
and trees. The leaves are often opposite and the wood is oxidising, i.e. it quickly turns orange to red-brown when cut. The leaves often dry dark grey and the venation is indistinct; the
indumentum of the terminal bud is rich brown in color. The tubular, petal-like perianth with its
induplicate-valvate or contorted aestivation is distinctive. The fruit proper, an achene, is
covered by the usually accrescent basal part of the perianth, and this in turn may be covered by glands that produce a very sticky secretion.

Evolution.Ecology & Physiology. A xerophytic clade in S.W. North America is noted for its abundance in dry or desert conditions. A number of species also tolerate gypsum-rich soils (esp. Abronia - see Saunders & Sipes 2011), and diversification of a desert clade of Abronia may have begun in the Oligocene or Miocene (Drummond et al. 2012).

The origin of C4 photosynthesis in Boerhavia and Allionia has been dated to within the last 7 m.y. (Christin et al. 2011b).

Pollination Biology & Seed Dispersal. The single-flowered inflorescences of some species of Mirabilis can look remarkably like individual flowers: The green inflorescence bracts appear to be a calyx, and the brightly-coloured connate perianth looks like a sympetalous corolla. Taxa that flower in the evening or night (hence the name, the "four o'clock family") are quite common (Douglas & Manos 2007); Nores et al. (2013) summarize pollination biology in the family.

The subepidermal cells of the perianth may produce mucilage when the fruit is wetted, and this is especially notable in disseminules of the xerophytic North American clade. In species like Pisonia the pericarp becomes viscid and very sticky indeed; it is used as bird lime to catch birds.

Bacterial/Fungal Associations. Pisonieae like Neea and Guapira and Pisonia are recorded as forming ectomycorrhizal associations with various basidiomycetes; in forests, the species involved are often quite dispersed (Haug et al. 2005; Tedersoo et al. 2010a).

Chemistry, Morphology, etc. Primary stem anatomy can be complex in those species with medullary vascular bundles (e.g. Pant & Mehra 1963); I am not totally clear what is going on at the nodes, but secondary thickening may also be involved. Carlquist (2004) examined secondary thickening in Nyctaginaceae in detail: there is a lateral meristem that produces secondary cortex to the outside, and to the inside rays, conjunctive tissue, and a succession of vascular cambia, from which the more or less isolated areas of vascular tissue (but not rays) are derived. Hernández-Ledesma et al. (2011) looked at anatomical variation within Mirabilis in some detail.

Some Nyctaginaceae (Boerhavinae, Nyctagineae) have pollen grains ca 200 µm long, about the largest in angiosperms outside the aquatic Cymodoceaceae (Alismatales). For nectaries in the family, see Nores et al. (2013). The single ovule seems to terminate the apex of the stem (Sattler & Perlin 1982). Abronia has only a single well-developed cotyledon, while the cotyledons of Pisonia and its relatives are unequal in size (and the embryo is straight).

See Rocén (1927) and Woodcock (1929) for ovules, Hegnauer (1968, 1990) for chemistry, Vanvinckenroye et al. (1993) for floral development, and Bittrich and Kühn (1993) for
general information.

Phylogeny. The South American Leucastereae and Mexican-Central American Boldoeae are successively sister taxa to the remainder of the family, positions that have moderate to strong support. Within the remainder of the family a North American xerophytic clade has very strong support. Here Bougainvilleae and Pisonieae (and minor additions) form a clade, while Abronieae are embedded in a highly paraphyletic Nyctagineae plus Boerhavieae complex, all these making up Nyctagineae above (Douglas & Manos 2007; see also Levin 2000 for a more limited study).

Classification. For the tribal classification, see Douglas and Spellenberg (2010); they also recognised a monotypic Caribeeae Douglas and Spellenberg, but this was not placed in the phylogeny.

Age. The age of crown group Molluginaceae is estimated at ca 46.7(± 4.8) or 50.3 (± 5.8) m.y.a. (Christin et al. 2011a).

Molluginaceae are herbs or subshrubs with pseudoverticillate leaves that often have scarious stipules, flowers that may be quite showy but which generally lack any corolline whorl, and seeds that lack an obviously long funicle.

Evolution.Divergence & Distribution. The rate of diversification of the Adenogramma-Pharnaceum clade is notably less than many others in this general area of Caryophyllales (Arakaki et al. 2011).

Ecology & Physiology. C4 photosynthesis probably arose more than once here (Christin et al. 2010b, 2011, q.v. for dates). There are also a few C3/C4 intermediates with C2 photosynthesis in Mollugo, and species such as Mollugo verticillata that photosynthesize like this may be some 10-20 m.y. old (Christin et al. 2011a). Adoption of the new photosynthetic pathway is accompanied by an increase of tolerance of drier conditions (Christin & Osborne 2014).

Chemistry, Morphology, etc. Anthocyanin presence should be confirmed; pigment type is largely unknown from the group (Brockington et al. 2011). The apparent anomalous occurrence of vascular rays in genera like Macarthuria (M. Endress & Bittrich 1993) is less anomalous when these genera are removed from the family; there has been a similar clarification of apparent variation in sieve tube plastid type. Para- dia- and anisocytic stomata
are all recorded; stomatal type should be checked against the new circumscription of the family. The stipule-like structures need examination.

The androecium may be
fasciculate; Adamson (1958a) noted that the 20-30 stamens of Hypertelis spergulacea, which belongs here, are in groups.

Phylogeny. Nepokroeff et al. (2002) found that Mollugo and relatives and Pharnaceum and relatives each formed a well-supported clade, but the two were only weakly linked. However, support for a monophyletic Molluginaceae was strong both in Christin et al. (2011a) and Arakaki et al. (2011), and resolution of relationships within the clade was also good; branches in the Adenogramma-Pharnaceum clade were notably long (Arakaki et al. 2011).

Classification. The limits of the family have long been
unclear. Most Molluginaceae as circumscribed in M. Endress and Bittrich (1993) are included here, but Limeum and relatives Limeaceae), Corbichonia (Lophiocarpaceae), and Macarthuria, are elsewhere in the core Caryophyllales. Polpoda is not incorporated in any description. It has P 4, A alternating with the perianth, G [2], basally connate styles, and scarious stipules (Hoffman 1994). There have been suggestions that Gisekia might be included in Phytolaccaceae-Rivinioideae (see Cuénoud et al. 2002), although here it is in its own family (Brockington et al. 2009).

Age. An estimate of the age for this clade is (33.7-)18.8(-6.7) m.y., not very old (Ocampo & Columbus 2010), (47.6-)44.9(-42.2) m.y. (Arakaki et al. 2011), or about 42.6 m.y. (Magallón et al. 2015).

Evolution.Divergence & Distribution. This clade seems to be New World in origin (Ocampo & Columbus 2010). Hershkovitz
and Zimmer (2000) suggested that there must have been a number of major dispersal/colonization events.

Ecology & Physiology. Ocampo and Columbus (2010) discuss the evolution of various photosynthetic pathways in this clade, which they reconstruct as being plesiomorphically C3. For CAM in the old Portulacaceae s.l., so scattered through this clade, see Guralnick and Jackson (2001) and especially Ocampo and Columbus (2010). CAM cycling is common; this occurs when plants do not completely shut their stomata during the day, and carbon is fixed at night not from atmospheric but from respiratory CO2.

For estimates of the numbers of succulent species in the various families, see Nyffeler and Eggli (2010b). Taxa with fleshy roots are scattered throughout the clade, being found in all families (except the monotypic Halophytaceae) as well as in all subfamilies of Cactaceae (e.g. Nyffeler et al. 2008).

Chemistry, Morphology, etc. Variation within this clade is complex (see also Nyffeler 2007, especially Ogburn 2007; Nyffeler et al. 2008; Ogburn & Edwards 2009; Nyffeler & Eggli 2010b; Ocampo & Columbus 2010). Most taxa have mucilage cells, but there may be interesting variation within the group as to exactly where such cells occur in the plant (Ogburn & Edwards 2009). For the distribution of peripheral vascular bundles in the leaf, i.e., the leaf venation is three dimensional, see Ogburn and Edwards (2013).

Interpretation of the parts surrounding the flowers is complicated by how they have been described. Often there are paired structures borne immediately below the flower and more or less completely surrounding it. Called bracteoles here, they have often been called sepals. Flowers often have more than a single pair of bracteoles. The inner/upper pair of bracteoles is in the median plane (e.g. Eichler 1878), as is the sole pair of bracteoles in Montia (Ronse de Craene 2010) and Halophyton (Pozner & Cocucci 2006), although they do not comment on the orientation. The transverse (outer, lower) bracteoles may have flowers in their axils, the inner
median bracteoles always lack them. In at least some species of Anacampseros the upper bracteoles are in the same plane as the bud-subtending bracteoles (Vanvinckenroye & Smets 1999), while in species of Portulaca such as P. oligosperma there are two quite large bracteoles immediately underneath the flower and then four smaller bracteoles in a whorl separated from the first pair by a short internode (Geesink 1969).

The whorl inside the bracteoles, usually 4- or 5-parted - perianth here - is like that of other core Caryophyllales. However, its members are often more or less brightly coloured and have been called petals or petal-like; in some taxa, at least, their development is much retarded relative to that of the androecium (dos Santos et al. 2012).

Portulaca has an androecial ring primordium, as in some Cactaceae and in species of Anacampseros, sometimes also with centrifugal initiation of stamens; other species have fewer stamens, which may be initiated in pairs (facing each other!) opposite the perianth members, or as single stamens alternating with them (Vanvinckenroye & Smets 1999). When there is the same number of stamens as perianth members, their position relative to the carpels varies. Nowicke (1996) summarized a number of pollen characters that are shared in the group (her Portulacinae), although they might also occur outside it: Columellae either narrowed towards the middle or expanded towards the base, sometimes fused; pollen with granular internal surfaces; perforated foot layer; non-apertural endexine "thread-like" - the latter term unclear from the descriptions provided.

For chemistry, see Hegnauer (1969, 1990), for anatomical information about the old Portulacaceae, see Becker (1895), for pollen, see Nilsson (1967), for general information, see Carolin (1987 [also a phylogenetic analysis], 1993). For information on the vegetative plant, see Nyffeler et al. (2008).

Phylogeny. Relationships between members of this clade were for some time rather uncertain, but it was clear that they were not reflected by the then-current classifications. Hershkovitz and Zimmer (1997) realized that if Cactaceae were recognised, Portulacaceae would be paraphyletic (see also Appelquist & Wallace 1999, 2001). Later they found little major phylogenetic structure in a study of American Portulacaceae (Hershkovitz
& Zimmer 2000: ribosomal DNA, Cactaceae not included). Hershkovitz (2006) found the same general pattern as he focused on W. American "Portulacaceae" from the Andean region - there were perhaps half a dozen clades in that region, but no major groupings beyond that. Cactaceae, Didiereaceae and Portulacaceae remained a closely entwined complex (Appelquist &
Wallace 2000). Indeed, they can all be intergrafted (Anderson 1997). See also Cuénoud et al. (2002) for relationships in this area, e.g. of Halophytum. Many of the relationships found by Ocampo and Columbus (2010) were poorly supported, and Halophytaceae were wandering around the tree.

A number of studies since 2007 have clarified relationships. Cactaceae + Talinum + Portulaca + Anacampseros, etc., were found to make up a major and rather well supported clade (Hershkovitz & Zimmer 1997; Appelquist & Wallace 2001). Nyffeler (2007: three genes, two compartments) found some support for a topology [Talinum and relatives [Portulaca [Anacampseros and relatives + Cactaceae]]], although the topology was different when the mitochondrial nad1 data were analyzed alone. Support for the [Anacampseros and relatives + Cactaceae] clade was appreciable in the combined analysis (78% bootstrap), where the chloroplast signal predominated.

Details of relationships around Cactaceae remained unstable. Brockington et al. (2009; large amounts of data, rather skimpy sampling) found a clade [Portulacaceae + Talinaceae] with 98% boostrap support, and Claytonia was sister to the whole clade, which included Halophytaceae. Nyffeler and Eggli (2010a) found few resolved relationships except in the Talinaceae-Cactaceae area, and support for the monophyly of Didieraceae and Montiaceae was not strong; and Butterworth and Edwards (2008) found the relationships [Anacampserotaceae [Talinacaeae [Portulacaceae + Cactaceae (weak support)]]], although there was no outgroup, so Anacampserotaceae appeared to be paraphyletic. Crawley and Hilu (2013) recovered the clade [Portulacaceae [Anacampserotaceae + Cactaceae]]. Portulaca and Pereskia (but
not Claytonia) share a 500 bp chloroplast DNA deletion in the rbcL gene (Wallace & Gibson 2002 for details and references), a potentially informative molecular marker.

Using the nuclear PHYC and chloroplast trnK/matK genes and ca 250 species of this clade, Arakaki et al. (2011) confirmed with strong support the position of Molluginaceae as the sister taxon of the clade under immediate discussion here (see also Soltis et al. 2011: support only moderate). There was strong support for relationships along the spine of this clade, but "only" 78% likelihood bootstrap support for the [Anacampserotaceae [Portulacaceae + Cactaceae]] clade, although that also has some morphological support. Support for the monophyly of all families is strong. The only exception is the [Halophytaceae [Didiereaceae + Basellaceae]] clade; Didiereaceae are not monophyletic, Basellaceae being sister to the Portulacaria group, and Halophytaceae are only weakly associated with the other two families (Arakaki et al. 2011). Soltis et al. (2011) found only weak support for the [Didiereaceae + Basellaceae] clade, but Anton et al. (2013) found some support for a [Didieraceae [Halophytaceae + Basellaceae]] clade.

Classification. Basellaceae and Didiereaceae are kept separate; a few African genera of Portulacaceae are included in the latter, so making them less distinct, although morphology is largely consistent with their new position. Portulacaceae are strongly paraphyletic, and erstwhile members are placed in Portulacaceae s. str. (now a small group), Talinaceae, Anacampserotaceae and Montiaceae below. The morphologically rather distinctive and Antipodean Hectorellaceae are included in Montiaceae.

For family limits and characterisations, see Nyffeler and Eggli (2010b).

Evolution.Ecology & Physiology. Within this clade, Montiaceae are noted for their ecological expansion into both colder and more seasonally variable habitats, and there have been several habit/habitat shifts within the clade (Ogburn & Edwards 2012). Calandrinia polyandra (= Parakeelya) is a facultative CAM plant (Winter & Holttum 2014).

Pollination Biology & Seed Dispersal. The seeds may be forcibly ejected as the margins of the valves incurve during capsule dehiscence (Carolin 1993). The seeds of some Montiaceae are myrmecophytic (Lengyel et al. 2010).

Bacterial/Fungal Associations. The South American Calandrinia is a host of the anther smut Microbotryum (Uredinomycota), also found on Silene, etc. (Hood et al. 2010).

Chemistry, Morphology, etc.Hectorella has both spiral phyllotaxis and a closed vascular system, a very unusual combination (Beck et al. 1982).

The inflorescence of Hectorella and Lyallia may be a reduced cyme; there are alternate/2-ranked bracts below the flower, and the latter genus may have more than one flower per axil (Skipworth 1961; Wagstaff & Hennion 2007). The paired bracteoles below the flower in these two genera are clearly described and illustrated as being transverse (lateral) by Skipworth (1961), but later described as being ad/abaxial (median) by Philipson and Skipworth (1961). Cave et al. (2010) described the lower two bracteoles of Calandrinia as developing successively, the upper pair being lateral(-abaxial). Montiopsis can have trilobed bracteoles. Nyffeler and Eggli (2010b) described the flower of Lewisia as having up to 9 "sepaloids" (= perianth members). Dos Santos et al. (2012) noted that the petaloids in Claytonia appeared well after the androecium was initiated; however, they thought that they were calycine, but with very delayed growth, rather than outgrowths of the filaments.

Schnizlein (1843-1870: fam. 206) showed carpels
alternating with the perianth members, or the median member in the abaxial position, as in Claytonia. Seed coat anatomy needs more study. Rocén (1927) thought that the endotegmen of Calandrinia (it looks like the exotegmen) had rod-like rhickenings; the tegmen was multiplicative. Claytonia virginiana has
extremely variable chromosome numbers - 2n = 12-ca 191 (Bogle 1969).

Some additional information is taken
from Philipson (1993) and Lourteig (1994); see Meunier (1890) for ovules and seeds, for pollen, see Nilsson (1967); see Carolin (1993) and Nyffeler and Eggli (2010b) for general accounts.

Phylogeny. For the circumscription of Montiaceae, see above. West American members of the old Portulacaceae to be included in Montiaceae include Montia, Lewisia, Phemeranthus (this used to be included in Talinum - Talinaceae here), etc. (e.g. Hershkovitz 1993, 2006; Hershkovitz & Zimmer 2000). Applequist et al. (2006: ndhf analysis, see also Nepokroeff et al. 2002) also included the New Zealand-Antarctic Hectorellaceae, previously of uncertain relationships, as a new tribe of Portulacaceae. The whole clade has strong support, as does the sister group relationship between Phemeranthus and the nine other genera included (Applequist et al. 2006; see also Ocampo & Columbus 2010). Although flower position (axillary) and bracteole and
stamen position of Hectorellaceae differ from that of other Montiaceae and the gynoecium is unilocular, the anatomy of the two is very similar (Carlquist 1998b). Phemeranthus has peripheral vascular bundles in the lamina with the xylem external (Ogburn & Edwards 2013).

Chemistry, Morphology, etc. There are no endothecial thickenings at all on cells adjacent to the openings of the anthers (Pozner & Cocucci 2006).

Some information is taken from
Bittrich (1993b) and Nyffeler and Eggli (2010b), general; for stomata, see Di Fulvio (1975); Pozner and Cocucci (2006) describe the staminate flower in considerable detail, including the distinctive endothecial thickenings and anther dehiscence.

Previous Relationships. Halophytaceae were included in Chenopodiaceae (Cronquist 1981). Relationships with Aizoaceae - also with rayless wood - have been suggested (Gibson 1978).

Didiereaceae are often more or less stout-stemmed plants usually with short shoots and deciduous leaves; theplant may have thorns. The flowers are usually imperfect and the one-seeded fruits are usually indehiscent.

Age. The age for crown-group Didiereaceae is (24.4-)12.1(-2.4) m.y. (Ocampo & Columbus 2010).

Chemistry, Morphology, etc. Rauh (1983) calls the spiky structures of Didiereaceae s. str. spines, being either
leaves on short shoots or paired and stipular. However, Alluaudia has leaves subtending an axillary spiky structure,
and later paired and apparently prophyllar leaves develop from an axillary bud
below it. This suggests that the spiky structure is a modified axillary shoot, a thorn.

The bracteoles immediately associated with each flower are
in the median plane, and large bracteoles of the inflorescence ("large bracts") may be obvious, as in Portulacaria. In Didiereaceae s. str. there are four stamens clearly alternating with the perianth members.

Phylogeny. This clade includes a morphologically distinctive monophyletic group of four Madagascan genera, Didiereaceae in the old sense, and immediately basal to them are some African ex-PortulacaceaeR. elationships are [Portulacaria [Calyptrotheca + Didiereaceae s. str.]], and within the last group, Allaudiopsis is sister to the rest, while the position of Decarya has only weak support (see e.g. Bruyns et al. 2014b).

Classification. Didiereaceae are expanded to include some ex-Portulacaceae (see Appelquist & Wallace
2000, 2003); Appelquist and Wallace (2003) provide a rather overelaborate subfamilial classification. See also Bruyns et al. (2014b) for genera.

Age. The age for this clade is some (26.6-)14.3(-5.1) m.y. (Ocampo & Columbus 2010) or (39.6-)37(-34.4) m.y. (Arakaki et al. 2011).

Chemistry, Morphology, etc. The axillary hairs in many of the first two families are bi- or oligoseriate, while those of the few Cactaceae examined - but from three subfamilies - are uniseriate, although those of Pereskiopsis are biseriate at the base. Chorinsky (1931) remains a useful early study on these structures, which are never vascularized (see also Rutishauser 1981). There is variation in the chloroplast infA gene in this clade, with both insertions and duplications occuring (Ocampo 2009).

Anacampserotaceae are often rather small, fleshy plants with two "sepals" surrounding five "petals", rather complex fruits in which two layers of the pericarp separate periclinally, and pale-coloured seeds in which two layers of the seed coat also separate periclinally.

Evolution.Divergence & Distribution. For the biogeography of this widely scattered clade, see Gerbaulet (1992b).

Ecology & Physiology. For the ecology of African Anacampserotaceae, see Gerbaulet (1993).

Chemistry, Morphology, etc. For general information, see von Poellnitz (1933), Gerbaulet (1992a), Rowley (1994), and Nyffeler and Eggli (201a, b); for anatomy, etc., see von Poellnitz (1933), for floral development, see Vanvickenroye and Smets (1999), and for some ovule morphology, see Rocén (1927).

Phylogeny. Nyffeler (1997) included six species of Grahamia in his study, and they formed a perfect pectination; at least some of the nodes had good support. This helps in reconstructing the basal character states for the clade - whatever characters Grahamia in the old sense had, those are the characters of the whole family.

Portulacaceae are succulent herbs with capitate inflorescences, flowers apparently with two sepals and usually five conspicuous petals, and circumscissile capsules.

Evolution.Ecology & Physiology. There have been several switches to C4 photosynthesis at a maximum of ca (33.8-)28.8(-23.8) m.y.a. (Ocampo & Columbus 2009) and at a minimum about 1/3 this time (Christin et al. 2011b). Ocampo et al. (2013) subsequently suggested perhaps a single origin there that could be dated to ca 23 m.y.a.; C3-C4 intermediates may be derived. They noted that there were two C4 subtypes and three anatomical variants in the genus (see also Voznesenskaya et al. 2011), and there are also facultative CAM/C4 plants (Winter & Holtum 2014). Christin et al. (2014b, q.v. for ppc-1E1 duplication) suggested that CAM evolved before C4 photosynthesis here.

Chemistry, Morphology, etc. The development of the perianth is much retarded relative to that of the androecium (dos Santos et al. 2012).

See Sharma (1954) for floral anatomy (the single traces to the P members divide into three), Meunier (1890), Rocén (1927), Kajale (1940c) and Ocampo (2013) for ovules and seeds, and Nyffeler and Eggli (2010b) for general information.

Phylogeny. Relationships within Portulaca are discussed by Ocampo and Columbus (2009). The genus consists of a clade with opposite leaves, in turn made up of Australian and African-Asian clades, and a clade with spiral leaves (Ocampo & Columbus 2012; Ocampo et al. 2013).

Classification. For included genera, see Nyffeler and Eggli (2010b).

Previous Relationships. For taxa included in earlier circumscriptions of Portulacaceae, see e.g. Carolin (1993) and Nyffeler and Eggli (2010b).

Age. Arakaki et al. (2011) suggest an age of (21.7-)19.7(-17.7) m.y. for this node.

Synonymy: Cereaceae de Candolle & Sprengel

Cactaceae can be recognised by their usually stout and
very fleshy stems, axillary areoles of spines and hairs, and flowers that usually have an
inferior ovary and many stamens and "petals"; the fruits are fleshy.

Evolution.Divergence & Distribution. Arakaki et al. (2011) note a number of clade ages and diversification rates within Cactaceae, and many of the latter are quite high, with significant radiations occuring in the late Miocene-Pliocene, ca 8-3 m.y.a. The Pachycereae, which include the North American columnar cacti, also began diversifying about then (ca 8.5 m.y.a.: Barba Montoya et al. 2011). Hardly surprisingly, the monotypic Blossfeldia, sister to all other Cactoidaeae (see below), represents a lineage with notably lowered diversification rates of 0 or 2.27 x 10-17/ma, depending on the particular measure used (Arakaki et al. 2011)! Crown group Opuntia in the narrow sense, with 150-180 species, may be (7.5-)5.6(-3.6) m.y. old (Araki et al. 2011). Originating in southwest South America, it may have moved to North America by long-distance dispersal, and it subsequently diversified there considerably (Majure et al. 2012). See also Nyffeler and Eggli (2010a) for some dates.

Cactaceae are an iconic family of the New World, but Rhipsalis,
epiphytic and bird-dispersed, has a few species growing in Africa, Madagascar, and Sri Lanka; there have been questions as to whether the Old World species are native, or not (Barthlott 1983).

As Edwards et al. (2005) note, the anatomy of the outgroups to Cactaceae is poorly known, as is the occurrence of proliferating inflorescences in Portulaca, also with a more or less inferior ovary and now thought to be sister to Cactaceae (c.f. Edwards et al. 2005).

Ecology & Physiology. Edwards and Donoghue (2006; see also Edwards 2006; Edwards & Diaz 2006; Ogburn & Edwards 2010) discuss the eco-physiological evolution of Cactaceae (for which, also see Nobel 1988 and references). They emphasize that the leafy Pereskia and Rhodocactus clades have high photosynthetic water use efficiency, very high minimum leaf water potentials (water movement is easy), and conservative stomatal behaviour, the stomata opening only when there is available water, at night or after rain. Other features of potential functional interest include the production of large amounts of water conducting tissue relative to leaf area, and perhaps also CAM-type photosynthesis. This latter is poorly developed in Pereskia, etc., but is well developed in succulent cacti (Martin & Wallace 2000).

Most Cactaceae have a broad and shallow rooting system that allows quick uptake of water after rain. In a number of Cactaceae, especially Cactoideae but not Pereskia s.l., the primary root is determinate in growth (Shishkova et al. 2013 for the rather erratic distribution of this feature), perhaps facilitating the rapid development of lateral roots (Rodríguez-Rodríguez et al. 2003). "Rain roots", water-absorbing roots, develop quickly after rains and die when the soil dries up. Here, too, the main root usually aborts (Shishkova et al. 2008; Ogburn & Edwards 2010), but a skeletal root system of perennial, cork-covered roots persists (Gibson & Nobel 1986). Contraction of the roots, so keeping the plant close to the ground surface, is known or suspected for some Cactoideae (Garrett et al. 2010). Roots in at least some Cactaceae have rhizosheaths surrounding and adherent to the root and perhaps protecting it against dessication; they are formed by mucilage from the root, soil grains, etc. (Huang et al. 1993).

Fleshy, water-storing roots are scattered in Cactaceae, including Pereskia (e.g. Rauh 1979); the taxa involved are usually small plants. The tissue involved is not always the same, suggesting the independent origin of such roots, but it is some kind of modified secondary vascular tissue (Stone-Palmquist & Mauseth 2002). These swollen roots seem to be particularly common in the taxa of the basal pectinations of Opuntioideae (Griffith & Porter 2009), and they are also scattered throughout in families in the clades immediately basal to Cactaceae as a whole (see also Griffith 2004).

Diversification of the "leafless" Cactaceae may be as much connected with the development of a cauline water storage system as with the evolution of the other ecophysiological features just mentioned (and of course one would like to know much more about the physiology and anatomy of the clades immediately basal to Cactaceae). The ribbed and/or tuberculate stems of most Cactoideae allow the loss and gain of large amounts of water as the stem can easily contract or expand (see also Mauseth 2006a). Few cacti are really dessication tolerant, although the diminutive Blossfeldia is an exception (Barthlott & Porembski 1996; Griffith 2009). Finally, although Cactaceae are pre-eminently a group of drier climates in the New World and a notable component of seasonally dry tropical forests (Pennington et al. 2009), a number of Cactoideae grow in more or less humid forest as lianes and epiphytes, several having flattened and leaf-like stems; the epiphytic habit may have evolved four times or so there (Korotkova et al. 2010).

Branched columnar cacti (and opuntioids) have constrictions where the branch joins the stem, which would seem to be rather hazardous biomechanically. However, Schwager et al. (2013) show how details of thickening pattern, fibre orientation, etc., make this constriction of the three Cactoideae that they studied biomechanically more plausible. Interestingly, these species may not have tension wood. For details of the ecology of columnar cacti, including drought tolerance, photosynthetic rate, germination and seedling establishment, see papers in Fleming and Valiente-Banuet (2002) and Williams et al. (2014).

Calcium oxalate metabolism in Cactaceae and relatives is potentially interesting. There is variation in the degree of hydration of calcium oxalate. There are two crystal forms, weddellite (CaC2O4.2H2O) and whewellite (CaC2O4.H2O); Cactoideae alone have weddellite (Rivera and Smith 1979: they note only druses were examined; Monje & Baran 2002; esp. Hartl et al. 2007). Some Cactaceae accumulate positively massive amounts of calcium oxalate crystals, for example, they make up ca 85% of the dry weight of Cactus senilis.

On a totally different subject, grafts between taxonomically widely distant taxa are easy to make in Cactaceae. For instance, Blossfeldia can be grafted onto Pereskiopsis, and contamination of Blossfeldia DNA by that of its stock was fingered as a possible cause of early conflicts over the phylogenetic position of that remarkable genus (Gorelick 2004).

Pollination Biology & Seed Dispersal. The evolution of a sort of hypanthium and so the possibility of developing a long floral tube may have been a key innovation for Cactoideae allowing a greater diversity of pollinators for the flowers; Cactoideae are much more speciose than other clades in this phylogenetic area (Schlumpberger 2012). Bee pollination is probably plesiomorphic in Cactaceae; there have been perhaps ten bee-to-humming bird pollinator shifts and half as many bee-sphingid moth shifts, mostly in Cactoideae (Schlumpberger 2012). A variety of other pollinators visit cacti flowers, and about 200 species in 51 genera are pollinated by bats (Dobat & Peikert-Holle 1985); Fleming et al. (2009) conservatively list 42 species in 26 genera (for bat pollination in columnar cacti, see Arizmendi et al. 2002 and references: also other papers in the same volume). Almeida et al. (2013) looked at nectary morphology and nectar concentration in some Cactoideae with very different floral morphologies; species with more exposed nectaries had greater sugar concentrations, perhaps being bee-pollinated. The senita cactus, Lophocereus schottii, is actively pollinated by a pyralid moth Upiga virescens that lays an egg in some flowers leading to the loss of the fruit; other potential pollinators also visit the flowers (Fleming & Holland 1998; Holland & Fleming 1999).

Animal - mostly bird - dispersal of the fruits is very common in the family; Rhipsalis (see above for its distribution) has miseltoe-like fruits. In some Cactoideae in particular the seeds may germinate while still in the fruit, a form of vivipary (Cota-Sánchez et al. 2007).

Plant/Animal Interactions. The cactus-feeding habit may have evolved only once in the pyralid phycitine moths, although support is weak (Simonsen 2008: morphology only). The phycitines include the famous/infamous (it depends on where you live) Cactoblastis cactorum, unfortunately now introduced into the U.S.A. (see also Ervin 2012).

The Drosophila repleta species group has radiated on Cactaceae, the larvae growing on fermenting cactus tissues, whether cactus pads or the stems of columnar cacti (Oliveira et al. 2012); they moved on to this habitat from fermenting fruits perhaps 16-12 m.y.a. Some Drosophila will grow on only a single host, the latter containing sterols that can stand in for essential sterols missing from the ecdysone pathway of the insect (Lang et al. 2012). Rotting cacti provide habitats for numerous insects in the Sonoran desert region (Pfeiler et al. 2013).

Bacterial/Fungal Associations. Endophytic bacteria have been isolated from Cactoideae growing in the Sonora desert. These may help the cacti grow on rocks, and in vito fixation of nirtogen has also been observed (Puente et al. 2009; Lopez et al. 2011).

Vegetative Variation. The stout, more or less succulent stem that characterises Cactaceae - but even Pereskia has quite thick stems - results from primary or secondary thickening/expansion in the cortex, less often the pith (for which, see Troll & Rauh 1950; Boke 1954). There is considerable variation in growth form in the leafless Cactaceae, which range from often bizarrely-branched trees to tall and unbranched to flat-discoid to tussock-forming to stoloniferous ("Wandersprosse", Creeping Devils) and occasionally even rhizomatous plants (see e.g. Rauh 1979), and this is discussed in a phylogenetic context by Hernández-Hernández et al. (2011).

The rather ordinary-looking leaves of Pereskia and Rhodocactus represent the plesiomorphic condition for the family (but c.f. Griffith 2004, 2008). In Opuntioideae, the leaves of Pereskiopsis
are rather similar, while those of Quiabentia (the two may be sister taxa - e.g. Butterworth & Evans 2008) are terete, unifacial but
also persistent; such large leaves have probably been derived more than once in the subfamily (Griffith 2009; Griffith & Porter 2009; Ritz et al. 2012). In most other Opuntioideae the leaves are small, terete and deciduous. Stomata are restricted to leaves and the stem adjacent to areoles in leafy Opuntioideae (Griffith 2008). Indeed, although one commonly thinks of Cactoideae in particular as being leafless, Mauseth (2007) showed that most do have leaves, although they are up to only 1.5(-2.5) mm long when mature and so are mostly shorter even than the small, terete leaves of Opuntioideae. Despite their small size, Cactoideae leaves may have a rudimentary lamina with vascular tissue, stomata, etc. The leaf base is early distinguishable from the rest of the leaf, and its subsequent development results in the ribs and tubercles along the stem that are characteristic of so many Cactaceae (Boke 1954).

The spines and hairs that make up the areoles of Cactaceae represent a short shoot, and these short shoots may keep on growing and adding spines and even photosynthetic leaves, as in Pereskia. Mammillaria has dimorphic areoles: There are normal spiny areoles born on tubercules (hence the generic name) and spineless areoles that bear flowers that are found in the axils of the tubercules; see also Rauh (1979) for inflorescence development.

Genes & Genomes. There is likely to have been ancient hybridization in Opuntia (Majure et al. 2012).

Economic Importance. The cochineal insect, the sternorrhynchid Dactylopius, grows on Opuntia spp.. Opuntia also provides food, fodder for livestock, and seriously invasive species (e.g. Ervin 2012 for some references).

Chemistry, Morphology, etc. The roots of at least some Cactoideae have an open type of apical meristem (Rodríguez-Rodríguez et al. 2003). Given the width of their stems, it is not surprising that many Cactaceae have very broad apical meristems 400-1500 µm across, rather broader than those of other flowering plants (Gifford 1954; Clowes 1961: sampling poor), although they are only 80-329 µm across in Pereskia in particular (Boke 1954). The cortex is particularly variable in Cactoideae. Mauseth and Landrum (1997) commented on the apparently very long-lived epidermis in many Cactaceae, which may remain functional for hundreds of years. Cuticle waxes in the form of spiral rodlets
occur in Cereeae.

There is potentially interesting variation within the parallelocytic stomata "type" so common here. Wallace and Dickie (2002) thought that the stomata of Opuntioideae were unique; in both Pereskia and Opuntioideae the subsidiary cells do not, or only barely, overlap the ends of the guard cells, the "opuntioid" stomatal type (it could be called brachyparallelocytic), while in other Cactaceae subsidiary cells successively more broadly invest the poles of the whole stomatal apparatus. There is also variation in stomatal orientation. The stomata on the stems of Pereskia and Opuntioideae are oriented parallel to the long axis of the stem, while in Cactoideae they tend to be unoriented (Eggli 1984).

The inferior ovary of Cactaceae is a text-book example of receptacular epigyny, the tissue investing the ovary being of axial origin (Boke 1964; see also Tiagi 1963 and references). Thus in genera like Opuntia areoles arranged in spirals cover the inferior ovary; it is as if the ovary had sunk into the stem. In Pereskia nemorosa and a few other Cactaceae additional flowers may arise from the axils of the leaves or from areoles on the ovary, the proliferating infliorescences in the characterization above (Rauh 1979; Leuenberger 2008 - see also Tetragonia-Aizooideae-Aizoaceae). The hypanthium so conspicuous in some Cactoideae in particular is an elaboration of this axial tissue, while "petals" show all intergradations with arole-subtending leaves on the axial tissue surrounding the ovary. The evolution of this inferior ovary needs to be re-examined given the paraphyly of Pereskia s.l. and the probable position of Portulacaceae as sister to Cactaceae; some species of Pereskia s. str. have superior ovaries (see Rauh 1979; Edwards et al. 2005). Tiagi (1963) noticed that in Pereskia aculeata and P. sacharosa the course of the vascular tissue in the hypanthium was S-shaped, while in P. bleo and P. grandifolia it took the course of an inverted U, however, the significance of this is unclear, since members of the first pair belong to both Pereskia clades. Vascularization of "prophylls", bracts and perianth members of the flowers varies (Tiagi 1963).

The initial stages of androecial development may be as either separate, more or less spirally-arranged primordia, or a ring primordium (Leins & Erbar 1994b). Ovary placentation is variable. Placentae may alternate with septae, and/or be more or less basal; Leins and Schwitalla (1988) interpret the condition in which ovules are associated with incomplete septae proceeding from the ovary wall as the plesiomorphic condition for Cactaceae (see also Leins & Schwitalla 1986). The nucellus in Parodia may protrude through the micropyle (Rauh 1979). Cisneros et al. (2011) suggest that the inner integument of species of Hylocereus may be 4-5 cells across, but this is not readily to be seen in the images they provide.

For general
information, see Barthlott and Hunt (1993), Anderson (2001) and Nobel (2002); Hunt et al. (2006) provdes an excellent summary of the family, including a volume of superb photographs of nearly all species taken mostly in the wild. For chemistry, see Hegnauer (1964, 1989), for spines, see Schlegel (2009 and literature, morphology and structure), for general anatomy, see Terrazas and Arias (2003: esp. Cactoideae), for nodes, see Bailey (1960) and for wide-band tracheids in particular, see Mauseth (2004), Godofredo and Melo-de-Pinna (2008) and Arruda and Melo-de-Pinna (2010). For Pereskia s.l., see Neumann (1935: pollen, etc., development), Leuenberger (1986: general), and Mauseth and Landrum (1997: "relictual" anatomical characters). For Opuntioideae, see Hunt and Taylor (2002: general) and Stuppy (2002: see morphology); for general anatomy see Mauseth (2005), for wood anatomy, see Mauseth (2006c). For Maiheunia some information is taken from Gibson (1977: anatomy), Mauseth (1999: anatomy), and
Leuenberger (1997: general); Taylor (2005) is a good introduction. For Blossfeldia, see Barthlott and Porembski (1996). For floral morphology, see Ross (1982), for pollen, see Cuadrado and Garralla (2009), Leuenberger (1976: general) and Garralla and Cuadrado (2007: Opuntioideae), for ovules, etc., see Mauritzon (1934d) and Maheshwari & Chopra (1955), for seed morphology, see Barthlott and Voigt (1979), and for that of Cactoideae, see Barthlott and Hunt (2000).

For revisions of critical taxa, see work by Leuenberger, e.g. Leuenberger and Eggli (1999: Blossfeldia) and Leuenberger (1986: Pereskia and Rhodocactus, 1997: Maiheunia, 2008: update on the literature of all three). Calvente (2012) enumerated the taxa in Rhipsalis.

Phylogeny. The basic phylogenetic relationships within Cactaceae are still rather uncertain, and chloroplast and nuclear genes can suggest different major clades (see Butterworth 2006a and Nyffeler & Eggli 2010a for summaries). A study by Nyffeler (2002) found rather weak support for the subfamilies and that perhaps rather distressingly Pereskia was not clearly monophyletic. Edwards et al. (2005) confirmed that Pereskia s.l. was paraphyletic, which allowed them to shed new light on the evolution of the cactus habit (c.f. Butterworth & Wallace 2005 - topology different). For more details on the relationships of the major clades in Cactaceae, now all individually quite well supported, see Butterworth and Edwards (2008), Hernández-Hernández et al. (2011: position of Maihuenoideae unclear) and especially Arakaki et al. (2011); details of relationships in Bárcenas et al. (2011) were less clear, but only the trnK-matK region was examined.

For relationships within Opuntioideae, see Griffith (2002), Wallace and Dickie (2002), Butterworth and Edwards (2008), Hernández-Hernández et al. (2011) and especially Griffith and Porter (2009). The latter found the well-supported set of relationships [Maihueniopsis et al. [Pterocactus [terete-stemmed species + flat-stemmed species]]]; the leafy Pereskiopsis is in a derived position in the clade (c.f. e.g. Mauseth 2005 on its apparently plesiomorphous features). Ritz et al. (2012) examined the phylogeny and evolution of Andean species of Opuntia with terete stems.

Within Cactoideae, the distinctive Blossfeldia liliputana (= Blossfeldioideae Crozier) is sister to all other Cactoideae (Crozier 2004), and although there was initially some controversy over this position, it has been confirmed (e.g. Gorelick 2004; Mauseth 2006b; Butterworth 2006b; Arakaki et al. 2011). Hernández-Hernández et al. (2011) provide a quite detailed phylogeny of Cactoideae, although for the most part maximum likelihood bootstraps were low and maximum parsimony support still lower; earlier studies of Cacteae (Butterworth et al. 2002) and Mammillaria (Butterworth & Wallace 2004) faced the same problem. Vázquez-Sánchez et al. (2013) discussed the phylogeny of Cacteae. For the phylogeny and evolution of columnar Cactoideae, see Wallace (2002: Calymmanthiumis odd), for those of South American mountain cacti, see Ritz et al. (2007), for Gymnocalycium, see Meregalli et al. (2010) and Demaio et al. (2011), for Pfeifferia and relatives, see Calvente et al. (2011), for Rhipsalidae, see Calvente et al. (2011a, b: also character evolution), for Echinopsis see Schlumpberger and Renner (2012), for Echinocereus, see Sánchez et al. (2014), and for Rhipsalis, see Calvente (2012). See also Wallace and Cota (1996) for the rpoCI intron and Wallace and Gibson (2002).

Classification. Metzing and Kiesling (2008) summarize early (pre-DNA) studies in the family, and include reproductions of some remarkable evolutionary trees. For a recent classification of the whole family, genera and tribes being listed, see Nyffeler and Eggli (2010a).

Over the years, there have been major disagreements over generic limits, and depending on the author, the number
of genera occurring in the family varies by a factor of ten, and of the species by a factor of
two. For example, in Cactoideae a mere sixteen genera included all the species in the subfamily in 1903, but now as many as 116 genera may be recognized (Hunt 2002). Bárcenas et al. (2011) sampled quite extensively in the family and found that many tribes and genera in both the big subfamilies were not monophyletic: Only 4/6 and 14/36 genera of Opuntioideae and Cactoideae respectively for which two or more species were sampled turned out to be monophyletic. Floral traits often reflect pollinator preferences rather than clades, and growth habit is also labile (Schlumpberger & Renner 2012: Echinopsis area). Much phylogenetic work explicitly or implicitly has taxonomic implications (e.g. Korotkova et al. 2010; Calvente et al. 2011; and especially Bárcenas et al. 2011). For generic limits in Cacteae, see also Vázquez-Sánchez et al. (2013).

Opuntia has been broadly delmited, but Wallace and Dickie (2002) have suggested that it should be dismembered, with sixteen genera in Opuntioideae. The situation in Opuntioideae is indeed a mess, as is clear from the study by Griffith and Porter (2009). Hunt (1999, 2002) had earlier proposed the recognition of about eight broadly-delimited genera, roughly equivalent to tribes of other workers, which certainly makes sense pending sorting out the phylogeny of the group as a whole - and might also be a sensible final solution. Whether or not the stakeholders (Griffith & Porter 2009) can agree might be another matter.

Previous Relationships. Despite the distinctive appearance of the "leafless" cacti, the relationships of the family with other Caryophyllales has generaly been recognized.